Does your Competitor have a mag well installed?
If the answer is yes, remove the magazine and clear the firearm.
The illustration can be found in the owner's manual at the bottom of page 26 with figure 36b. Page 33 addresses removing that and refers to it as the retainer for the mag well in figure 70.
At the rear of the mag well, you should see a round post with a flat tab on one side.
Turn the flat tab toward the center of the mag well, about a quarter turn.
Grab the tab and pull out away from the gun. What you have removed is the assembly tool you're looking for. It is part of the firearm, not a separate tool you would find in a kit.
Once removed, you can change you grip modules.
Hope this helps, good luck and safe shooting.