I think you may not be able to. I don't think they're decals; I think they go deeper.
My reasoning for this is that I've turned down the joint end of a Predator before to get it to match to a few of my cues, taking off several thousands of an inch. That would have removed an ordinary decal, but didn't remove the Predator insignia. Not sure about other LD shafts, haven't had to alter one.
AFAIK most of them are decals. For example if you buy a Predator blank it comes with a decal. It is up to you if you have the cue maker that finishes the shaft put the decal on.
If it is already there, i would suggest having a reliable cue repair person remove it if you insist you don't want it.
Just got a new OB XL +. After a few months the OB label started to become less and less legible. It was not a true decal, and was only a sticky backed label which easily pulled right off. You'd never know it was ever there.