i need to return the uverse cable boxes

Since you lost the paperwork see below:

Here are the instructions from the AT&T website:

These steps are for U-verse customers returning leased equipment to:

• Reduce the number of AT&T U-verse TV receivers
• Discontinue your AT&T U-verse services
• Replace equipment

We've got a simple return process for leased equipment through The UPS Store:

1. Call us at 800.288.2020 during normal business hours for an order number and instructions for returning the equipment. This information will also be sent to you via email and/or by the U.S. Postal Service and will include detailed return instructions.
2. Take your letter and the equipment that you want to return to your nearest participating The UPS Store for final processing and packaging. They need the order number and account number found on the letter in order to process the return.
3. Don't package the equipment or create a shipping label yourself. Instead, let The UPS Store take care of shipping and handling for you at no additional cost! And please pay attention to these points: 
   • To make sure that your account is credited properly for the return, carefully follow the instructions within the letter.
   • Check your email/letter for a detailed list of items to be returned.

To find the closest The UPS Store in your area:

1. Visit The UPS Store online.
2. Enter your address or ZIP code in the Find a Location field.
3. Search results will be presented and you can scroll through the list of options to find the closest location.

If you need further assistance, call UPS at 800.789.4623 and ask for The UPS Store nearest you.

Thanks so much for choosing AT&T. We really appreciate it!