Prior to painting is it recommended to remove the screw inserts that hold the mirrors to the doors? These inserts are crimped on the doors.

If so, what is the recommended way to remove without damaging the hole size ?

Don't remove them

Run a bolt up from inside, then unscrew it after paint. Or, use a plastic/rubber plug from the inside. Or, just chase the threads with a tap after paint.

Im not worried about getting paint in the threads as I have old screws I can leave in place. But since the car is apart, whats 4 more inserts if it will benefit the overall paint job in that area.

Are they easy to remove ?
Any risk to the door holes ?

They are not easy to remove but if you feel the need I'd use a die grinder & cut the head off... Personally I'd leave them in...

You can remove them fairly easily (but carefully!) by using a drill of the correct size. It will take the head of the insert off and the back of the insert will fall out. Ideally you want to be careful not to let the drill bite and spin the head which may scuff the paint, but this can be done and if you are repainting not an issue. But I agree, no reason to remove if they are in working condition. (I needed to do this because one was incorrectly positioned...don't ask...)