"You Are Almost Out Of Data Storage Space"

Every Time I Start Minecraft, It Will Never Let Me Open A World, Open Marketplace, Or Join Servers And Or Friends. The Same Message Pops Up Every Time... "You are almost out of data storage space! Minecraft has restricted access to this feature untilyou lear up additional storage space." It Will Not Go Away And I Don't Know How To Get Rid Of It, I'm currently trying to delete worlds with gray preview windows. Still nothing.