Has anyone actually managed to remove a contact from a pending Manual Call (Power Dialer) task automatically?

Setup: contact enters Stage X → Manual Call action adds them to the dialer queue. When the stage changes to Y, I want the pending call task gone.

"Remove from Workflow" doesn't seem to clear the task from Conversations > Manual Actions, and I can't find a dedicated action for it. There's an open feature request for this on the ideas board.

But someone showed me a sub-account where it apparently does work: contact moves to Hot Lead and disappears from the dialer. The workflow is locked, so I can't see how it's built.

Has anyone got this working? If so, what's the actual setup?

Thanks!