1
general::
Stop working, abandon something, give up, as in John is calling it quits for now or This ground is far too stony for a garden so I'm calling it quits. This idiom comes from cry quits, dating from the 1600s and meaning "declare even" or "get even." The verb call was substituted in the late 1800s. Also see CALL IT A DAY.
American Heritage Idioms
2
general::
Phrase(s): call it quits
to quit; to resign from something; to announce that one is quitting. • Okay! I’ve had enough! I’m calling it quits. • Time to go home, John. Let’s call it quits.
McGrawhill's American Idioms And Phrasal Verbs