It really comes down to whether you want to discuss it or not.

If you don't really want to discuss it, then don't bring it up at all and just don't return. Just understand, you may get varying responses to just not ever coming back. Are you prepared to just have it stop and be okay with the therapist perhaps never inquiring of you why you haven't returned?

If you choose to just drop the end at the very end of your session, be prepared that the therapist may ask for you to come back for a session to discuss it anyway. Are you prepared to either say "No thank you, I don't really need to discuss this decision" or to accept one more appointment to discuss it.

If you just go ahead and bring it up at the beginning of the next session, it can all be discussed and over with by the time you leave. Personally, that would be my choice.