that will/should do itidiom
Definition of that will/should do it
1 —used in informal speech to tell someone that one does not want or need anything more "Would you like anything else?" "No, that'll do it." —sometimes shortened to that will/should do That should do, thanks.
2 —used to say that one has finished doing something or is about to finish doing something. I just have one more letter to sign and that should do it.