Completely removing/hiding wall switches
A perfect drywall job isn't an option, as you're not allowed to cover junction boxes or otherwise render them inaccessible. 

In the case of those switches which share a box with switches for other lights, you can find partial blank plates. However, these won't accomplish your goal of cleaning up the walls. 

In all cases you can nut the broken circuit legs together in a permanent fashion, but again, this alone doesn't accomplish your goal. 

Unless you can access the wire routes to completely remove the wiring back to the upstream box, you're more or less out of luck.