Just sold my Yugo 59/66, it's a great gun, very pretty beechwood stock, but I just never really was all that "into it". It's just
so heavy for the power of the cartridge.
I have a .308win, .270win. and 7mm Rem Mag that are all
far lighter and are more powerful cartridges. Course I guess none of them have attached grenade launchers and folding bayonets, either...
...if I get pinned down next season by a squad of deer with heavy MG support, I'll be wishing I had that grenade launcher back....
They're great guns, milled receivers, trigger groups and receiver covers, it shoot well, I even won a club service rifle (you should have seen their faces) match with it, I just never could get "into it".
To answer the question, yes, you can remove the grenade launcher; but I'd buy something else before I went to that trouble. As someone else mentioned, you can launch golf balls from it, and that's pretty darn cool...