You can close a PO Box by going to Manage PO Box, signing in to your account, and clicking the Close/Request Refund link next to the box. You can also request a PO Box be closed by informing the retail associate at the Post Office where your box is located. Once a box is closed, be sure to submit a Change of Address (COA) form. Your mail can be forwarded to your new address for up to one year.