1
general::
Take charge, assume control, as in Ever since Bill retired from the business, his daughter's been running the show. The word show here simply means "kind of undertaking." [First half of 1900s] A similar usage is run one's own show, meaning "exert control over one's own activities" or "act independently." For example, The high school drama club didn't ask permission to perform that play? they want to run their own show. [Mid-1900s]
American Heritage Idioms
2
general::
Phrase(s): run the show
to be in charge; to be in command. • Who’s running this show? • No, I don’t want to have to run the show again.
McGrawhill's American Idioms And Phrasal Verbs