I would remove them just like reefman has stated, by hand. It's farily easy to break off the rock but try not to break the bubble.
But you also should look into why they are growing, normally means excess of nutrients in the tank (overfeeding or such). I have some in my 65g and don't really care anything about the bubble algae but I'll remove it if I decide to move a piece of coral around and come across some bubble algae.
135g Main Tank/ 125g Frag tank with 55g sump.