To retract/withdraw an earlier statement
No, you are not fat; I take it all back.
To cause to remember some past event or time
That tune takes me back to my childhood.
To resume a relationship
She has forgiven him, and taken him back.
To regain possession of something
The wedding is off, and he has taken back the ring.
To return something to a vendor for a refund
Take back faulty goods to the shop where you bought them.