how can I remove a squirrel form our fireplace human (glass doors)?

This calls for professionals. Call animal control, as the little critters can shred anything they touch. The poor guy is probably scared, and without a clear path to outside, you can kiss your house goodbye.
If this is not an option, I would set up some heavy blankets around the fireplace doors, and pray that it will go in and not up your arm when you open the door.