If they are anything like the studs that held them on the bumper, it would not be worth the effort.
I changed them out with carriage bolts.
Not even sure the rubber is worth saving anyway. I think these studs are molded into the rubber. I'll get a good look at them and see if they are worth saving. The original inner bumper had big holes in it. Road salt was hell on these cars around here and back bumpers are one area that got the worst of it.