The tracks in the post and beams are covered by blanking strips. You are able to simply slide the blanking strips out of the posts. For the beams, or track removal after install, you can pop the strips out from the top/corner of the tracks using an Allen key.
Note: The black clips underneath each strip exist to hold the strip in place in the track. You should keep these if you want to reinstall the strip (e.g., cut it down to accommodate a heater and reinstall the part to cover up a portion of the track after install). If you are installing LEDs, these clips can be discarded.