Here's how you can remove your TPMS units at home. If you go in to a tire shop they might charge up to $20 a wheel to pull them and refill them with air. Here you can see what it takes to do it at home. I used an inexpensive tool for pulling a new valve stem into place. See below for a link to purchase one for yourself.
Valve stem tool
At Home Tpms Removal Without Special Equipment