once you're done with a patch....
-delete patch(assign only)
-delete patch from library (or dont assign to the library to begin with)
-choose optimize in the sample manager which cleans up all the samples that are just sitting in sample manager
it works the same if you import say 30 kicks, don't assign, just press "ok" they get put in sample manager. you assign/audition from there. and optimize cleans up everything you didn't use.
its that you asked how to do it on the mv but that's a pretty nice way of working actually

mass import kicks/snares to patches. listen what fits from the pads, no slow preview. easily discard unused drums.