How do I delete the actions cache?

[memchr]

The actions cache can be deleted with REST API, for example when running the workflows in a github hosted runner,

- name: Remove old build cache
        shell: bash
        run: |
          curl -H "Accept: application/vnd.github.v3+json" -H "Authorization: token $GITHUB_TOKEN" -X DELETE "$GITHUB_API_URL/repos/${{ github.repository }}/actions/caches?key=$CACHE_KEY"
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          CACHE_KEY: ccache

How do I delete the actions cache from the workflow using act?

[doubledup]

I'm not sure about a specific cache key, but you can set --cache-server-path in .actrc in each project so that cache deletions are project-specific. The default cache location is ~/.cache/actcache, so deleting that directory (or whichever directory you pass to --cache-server-path) will clear the build cache.