The bumpers have a rather mild adhesive on them. I don't see myself ever not using them, but I wouldn't worry about removing them. If anything a little goo remover might be needed. Also they go on the back side of the speaker, not a commonly seen part.

Pioneer PDP-5020FD, Marantz SR6011
Axiom M5HP, VP160HP, QS8
Sony PS4, surround backs
-Chris