What I do is carefully fold up one corner of the plastic before I stick it on. Only a very tiny amount. Less than a mm. Then when I need to remove the protector I can grip that corner with some fine tweezers to lift it and remove the protector. No need to try to get something between the screen and plastic then. No problem with residual glue. They seem to use very low tack adhesive. Trickiest thing is putting on the new ones without getting air bubbles or dust and hairs under the plastic. If something sticks to the underside of the protector before you put it on the screen you can't get it off.

Simon