(I've) got to go
I need to leave. Well, I've got to go. It was lovely to see you, as always. Got to go before I miss my train!
(I've) got to go.
a phrase announcing one's need to depart. (See also (I) have to shove off for other possible variations.) Andy: Bye, I've got to go. Rachel: Bye, little brother. See you. Sally: Got to go. Sue: See ya! Take it easy.