If it's blue or medium threadlocker, then as Husker said, a good fit and brute force will "break" it. If its the permanent type, like red loctite, you may have to put a soldering iron to the screw to heat it (or the bushing if you can get at it from the magwell) before you can move it.
The soldering iron and a very good screwdriver will help the screws come out. I have also soaked the frame in Liquid Wrench then the soldering iron. This may not be the best for the grips but it will help you break the screws loose without loosening the bushing or even worse eating the bushing.