Yep! To remove a program after you've joined, simply tap the menu icon in the upper left corner, choose "Settings" from the menu that displays, and tap "Manage my Memberships."
You'll then be taken to a list of all the programs you're a part of. Tap the program you'd like to remove, and tap "Remove this Program."
You can rejoin the program later if you'd like, but you won't receive another joining reward.