I am having trouble aborting / starting over.

I am having trouble aborting / starting over. I started running some GCode, but realized I had the wrong bit in so want to start over. Seems that nothing I can think to try will abort the job in process, which I think is necessary to zero work area (either g54 or g55 – I don’t know the difference) – Set G554 does nothing. Here is a screen shot: Any tips?