I have a lot of plastic anchor bolts in the sheetrock walls. What is the best way to patch them?
Depending on the design of them, if they're the type that can be removed ( pulled straight out with needle nose pliers) I would yank them then patch them.

If they are the type that don't want to come out easily, sometimes you can take a small ball peen hammer ( using the rounded end )and lightly tap them below surface level... This way, patching can be accomplished.

And finally, if you can't do anything with them  ( in rare cases ) you can drill them out gently, then of course patch.