Unfortunately, your best options are to cut off the tab and leave as is, or to remove the sheet of mylar.

I would shave off that little tab of mylar and then place a circle of removable mylar over that insert, cut to fit the black keyline so it doesn't show.

System 11 paint/inserts are notorious for flaking off so if you plan on taking any amount of mylar off you run the risk of losing the paint underneath. Best method IMO is freeze spray then adhesive remover. I have injected similar areas to what your seeing using a syringe and clearcoat as well as UV curing adhesive. injecting it will make it look much better but its hard to get it to be perfect. Problem with injecting it is that if anyone ever decides to remove the mylar it could be a problem in that area. Honestly though, if you remove mylar on a system 11 its a huge risk so I just commit to either keeping it or removing it and make my decision.