In Poser, you can open your hierarchy editor, 'x' the show all parameters box, find morphs you don't need, select them and hit delete on your keyboard (I think this deletes them from completely from the CR2 rather than just remming them out).

Additionally, you can use a program like CR2Editor to delete the morphs, and I think Morph Manager will do it as well. Of course make sure you're working with a copy of the cr2 and not the original V2 cr2.

Jaagar may have some more/better information on this, but I think you want to avoid deleting any PBM's associated with the FBM's you want to keep on the figure.

Hope this helps.