better be going
(I'd) better be going.and (I'd) better be off.
an expression announcing the need to depart. Bob: Better be going. Got to get home. Bill: Well, if you must, you must. Bye. Fred: It's midnight. I'd better be off. Henry: Okay. Bye, Fred. Henry: Better be off. It's starting to snow. John: Yes, it looks bad out.