Depending on the location of the screw, you may be able to grind the screw head completely off. Then once the part you are removing is completely out, you should have enough of a screw protrusion to be able to grip it with small pliers and turn it until it comes out. Again, this is quite advanced so you would have to be comfortable with working with a Dremel tool.
You can also get kits at home depot for removing stripped screws. There are ones that come with putty that you can apply to the screw head and then when it starts to harden you can push your screw driver into it to create an imprint. Once it dries the screw should come out reasonably easily.