Go into "your account" under where it says your name in the drop-down menu (top right-hand corner of the screen). You should have to reenter your password (unless you just logged in). Then it'll be in the column on the left hand side.hmm. i can't seem to find the cancel icon today. Can someone remind me where it is? I feel like it's usually very easy to find.
This is all assuming you're using the computer version. No idea how to do anything with mobile.