rein back on (something)
To attempt to restrict something or get something under control. We really need to rein back on how much we're spending on office supplies each month. I've been reining back on eating so much junk food lately.
rein back on someone or something
to control or diminish the intensity of someone or something. The manager was urged to rein back on her assigning overtime. She reined back on expenses and demanded that others do likewise.