support: is there a recommended workflow for cleanup after changing keep_files back to false?

[iandouglas]

Checklist

• I am using the latest version of this action.
• I have read the latest README and followed the instructions.
• I have read the latest GitHub Actions official documentation and learned the basic spec and concepts.

Describe your question

Hi folks,

We have keep_files set to true in a workflow, but now we need to find a way to clean up lingering PRs once we change this back to false ... is there a recommended clean-up process you can recommend, or steps to follow? Would love to get pointed in the right direction.

Relevant links

- name: Deploy to /gh-pages
         if: github.event_name == 'push' && github.ref == 'refs/heads/main'
         uses: peaceiris/actions-gh-pages@373f7f263a76c20808c831209c920827a82a2847 # pin@v3
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: documentation/build
           keep_files: true   # This preserves existing files in gh-pages branch especially for previews

# we want to change that to false, but how do we clean up the old files?

Relevant log output

we have a lot of previews here to clean up, but not sure of the process to delete them safely

Additional context.

No response