Run in bash (linux) or Git Bash (Windows)
Remove all workflows:
gh run list --json databaseId --jq ".[].databaseId" --limit 1000 | xargs -n1 gh run delete
Remove specific workflow:
gh run list --workflow "{Workflow name}" --json databaseId --jq ".[].databaseId" --limit 1000 | xargs -n1 gh run delete
You might need to run several times or adjust the limit (default is quite small)