Use a T5 Torx driver to remove the 13 screws securing the trackpad assembly:

Nine 5.8 mm screws

Four 4.9 mm screws

These screws look very similar, so don't mix them up.

These screws can loosen over time due to the clicking action on the Force Touch trackpad. Adding a little blue threadlocker as you install them can help keep them secure.

Install the screws loosely and check the trackpad alignment before tightening them down.