“If the renters policy was purchased by or through the apartment management, then the management should have provided you with a copy of the policy, including all policy details at the time that the insurance was purchased. A renters policy covers personal property and personal liability, so there would be no benefit to the property manager in keeping this policy in place if you have moved out.
I recommend contacting the insurance company noted on the paperwork, notifying them that you have moved, and requesting cancellation of the policy. You should inform the property manager of the cancellation as well.
You might also want to ask the insurance company if they can backdate the cancellation to the move-out date, or the date that the policy was no longer required. “