diff --git a/ui/src/hooks/useApi.ts b/ui/src/hooks/useApi.ts
index a991d7c..72cefe8 100644
--- a/ui/src/hooks/useApi.ts
+++ b/ui/src/hooks/useApi.ts
@@ -422,6 +422,17 @@ export async function getRunDetail(runId: string) {
   return resp.json()
 }
 
+export async function deleteRun(runId: string): Promise<{ ok: boolean; run_id?: string; detail?: string }> {
+  const resp = await fetch(`/api/benchmark/runs/${encodeURIComponent(runId)}`, {
+    method: 'DELETE',
+  })
+  const data = await resp.json().catch(() => ({}))
+  if (!resp.ok) {
+    throw new Error(data.detail || data.error || `delete failed: ${resp.status}`)
+  }
+  return data
+}
+
 export async function getHFModelDetails(repo: string): Promise<HFModelDetails> {
   const resp = await fetch(`/api/models/hf-details?repo=${encodeURIComponent(repo)}`)
   return resp.json()
diff --git a/ui/src/pages/RunDetailPage.tsx b/ui/src/pages/RunDetailPage.tsx
index 109310c..12962e3 100644
--- a/ui/src/pages/RunDetailPage.tsx
+++ b/ui/src/pages/RunDetailPage.tsx
@@ -1,6 +1,7 @@
 import { useEffect, useState } from 'react'
 import { useParams, useNavigate, Link } from 'react-router-dom'
 import ScoreBadge from '../components/ScoreBadge'
+import { deleteRun } from '../hooks/useApi'
 
 interface RunDetail {
   status?: string
@@ -27,6 +28,8 @@ export default function RunDetailPage() {
   const navigate = useNavigate()
   const [data, setData] = useState<RunDetail | null>(null)
   const [loading, setLoading] = useState(true)
+  const [deleting, setDeleting] = useState(false)
+  const [deleteError, setDeleteError] = useState<string | null>(null)
 
   useEffect(() => {
     if (!runId) return
@@ -107,6 +110,23 @@ export default function RunDetailPage() {
   const sm = run.speed_metrics || {}
   const machine = run.machine || {}
 
+  const handleDelete = async () => {
+    if (!runId || isRunning) return
+    const ok = window.confirm(`Delete local run ${runId}? This cannot be undone.`)
+    if (!ok) return
+
+    setDeleting(true)
+    setDeleteError(null)
+    try {
+      await deleteRun(runId)
+      navigate('/leaderboard')
+    } catch (err) {
+      setDeleteError(err instanceof Error ? err.message : 'Failed to delete run')
+    } finally {
+      setDeleting(false)
+    }
+  }
+
   return (
     <div>
       {isFailed && (
@@ -132,6 +152,12 @@ export default function RunDetailPage() {
         </div>
       )}
 
+      {deleteError && (
+        <div className="card" style={{ padding: 12, marginBottom: 16, borderColor: 'rgba(239,68,68,0.4)', background: 'rgba(239,68,68,0.06)', color: '#ff8888', fontSize: '0.85rem' }}>
+          {deleteError}
+        </div>
+      )}
+
       <div style={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', marginBottom: 16 }}>
         <div>
           <button
@@ -145,12 +171,31 @@ export default function RunDetailPage() {
             Run <code style={{ fontFamily: 'var(--mono)' }}>{runId}</code> · {run.timestamp || '—'} · harness <strong>{run.harness || 'raw'}</strong> · provider <strong>{run.provider || '—'}</strong>
           </div>
         </div>
-        <Link
-          to={`/compare?a=${encodeURIComponent(runId || '')}`}
-          style={{ background: 'var(--bg-elev)', border: '1px solid var(--border)', color: 'var(--text)', padding: '6px 14px', borderRadius: 6, fontSize: '0.85rem', textDecoration: 'none' }}
-        >
-          Compare with…
-        </Link>
+        <div style={{ display: 'flex', gap: 8 }}>
+          <button
+            onClick={handleDelete}
+            disabled={isRunning || deleting}
+            title={isRunning ? 'Cancel active runs before deleting them.' : 'Delete this local run'}
+            style={{
+              background: 'rgba(239,68,68,0.08)',
+              border: '1px solid rgba(239,68,68,0.35)',
+              color: isRunning ? 'var(--text-dim)' : '#ff9999',
+              padding: '6px 14px',
+              borderRadius: 6,
+              fontSize: '0.85rem',
+              cursor: isRunning || deleting ? 'not-allowed' : 'pointer',
+              opacity: isRunning || deleting ? 0.6 : 1,
+            }}
+          >
+            {deleting ? 'Deleting...' : 'Delete'}
+          </button>
+          <Link
+            to={`/compare?a=${encodeURIComponent(runId || '')}`}
+            style={{ background: 'var(--bg-elev)', border: '1px solid var(--border)', color: 'var(--text)', padding: '6px 14px', borderRadius: 6, fontSize: '0.85rem', textDecoration: 'none' }}
+          >
+            Compare with…
+          </Link>
+        </div>
       </div>
 
       {/* Top-line scores */}
diff --git a/ui/src/tabs/LeaderboardTab.tsx b/ui/src/tabs/LeaderboardTab.tsx
index 5806cf9..c2c1948 100644
--- a/ui/src/tabs/LeaderboardTab.tsx
+++ b/ui/src/tabs/LeaderboardTab.tsx
@@ -1,6 +1,6 @@
 import { useMemo, useState } from 'react'
 import { Link, useNavigate } from 'react-router-dom'
-import { useRuns } from '../hooks/useApi'
+import { deleteRun, useRuns } from '../hooks/useApi'
 import ScoreBadge from '../components/ScoreBadge'
 
 // "Full" = at least these quality suites + speed. Coding is optional bonus.
@@ -71,6 +71,8 @@ export default function LeaderboardTab() {
   const [providerFilter, setProviderFilter] = useState<string>('all')
   const [harnessFilter, setHarnessFilter] = useState<string>('all')
   const [rankMode, setRankMode] = useState<RankMode>('overall')
+  const [deletingRunId, setDeletingRunId] = useState<string | null>(null)
+  const [deleteError, setDeleteError] = useState<string | null>(null)
 
   const scoreOf = (r: RunRow): number => {
     switch (rankMode) {
@@ -110,6 +112,22 @@ export default function LeaderboardTab() {
   const totalRuns = ranked.length
   const filteredPartialCount = ranked.length - ranked.filter(isFullRun).length
 
+  const handleDelete = async (run: RunRow) => {
+    const ok = window.confirm(`Delete local run ${run.id}? This cannot be undone.`)
+    if (!ok) return
+
+    setDeletingRunId(run.id)
+    setDeleteError(null)
+    try {
+      await deleteRun(run.id)
+      refresh()
+    } catch (err) {
+      setDeleteError(err instanceof Error ? err.message : 'Failed to delete run')
+    } finally {
+      setDeletingRunId(null)
+    }
+  }
+
   return (
     <div>
       <div style={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', marginBottom: 16, padding: '8px 0' }}>
@@ -273,6 +291,21 @@ export default function LeaderboardTab() {
           ⚠️ {speedAtCapCount} runs have speed score at the 100 ceiling. Switch to "Raw tok/s" to see actual speed differences.
         </div>
       )}
+      {deleteError && (
+        <div
+          style={{
+            background: 'rgba(239,68,68,0.08)',
+            border: '1px solid rgba(239,68,68,0.3)',
+            color: '#ff8888',
+            padding: '8px 12px',
+            borderRadius: 6,
+            fontSize: '0.78rem',
+            marginBottom: 12,
+          }}
+        >
+          {deleteError}
+        </div>
+      )}
 
       {!loading && filtered.length === 0 && (
         <div className="empty-state">
@@ -362,12 +395,31 @@ export default function LeaderboardTab() {
                       {run.total_runtime_sec ? `${run.total_runtime_sec.toFixed(1)}s` : '—'}
                     </td>
                     <td style={{ ...cellStyle, textAlign: 'center' }} onClick={(e) => e.stopPropagation()}>
-                      <Link
-                        to={`/compare?a=${encodeURIComponent(run.id)}`}
-                        style={{ fontSize: '0.72rem', color: 'var(--accent)', textDecoration: 'none', padding: '4px 8px', border: '1px solid var(--border)', borderRadius: 4 }}
-                      >
-                        Compare
-                      </Link>
+                      <div style={{ display: 'flex', justifyContent: 'center', gap: 6 }}>
+                        <Link
+                          to={`/compare?a=${encodeURIComponent(run.id)}`}
+                          style={{ fontSize: '0.72rem', color: 'var(--accent)', textDecoration: 'none', padding: '4px 8px', border: '1px solid var(--border)', borderRadius: 4 }}
+                        >
+                          Compare
+                        </Link>
+                        <button
+                          onClick={() => handleDelete(run)}
+                          disabled={deletingRunId === run.id}
+                          title="Delete this local run"
+                          style={{
+                            fontSize: '0.72rem',
+                            color: '#ff9999',
+                            background: 'rgba(239,68,68,0.06)',
+                            padding: '4px 8px',
+                            border: '1px solid rgba(239,68,68,0.35)',
+                            borderRadius: 4,
+                            cursor: deletingRunId === run.id ? 'not-allowed' : 'pointer',
+                            opacity: deletingRunId === run.id ? 0.6 : 1,
+                          }}
+                        >
+                          {deletingRunId === run.id ? 'Deleting...' : 'Delete'}
+                        </button>
+                      </div>
                     </td>
                   </tr>
                 )