If you need to remove a tracking template, you can do so in your Google Ads account, based on the level you originally installed it on (account, campaign or ad level).

Removing tracking template on account level

Go to the "Account Settings" by clicking on the link in your sidebar (on the left side in Google Ads UI):

Open the "Tracking" panel, delete the tracking template and then hit "Save":

Removing tracking template on campaign level

Select the campaign you wish to change and go to "Settings" by clicking on the appropriate link in your sidebar:

Expand the "Additional Settings":

Open the "Campaign URL options" panel, delete the tracking template and then hit "Save":

Removing the tracking template on the ad level

Edit the ad you wish to change and expand the "Ad URL options" section on the bottom:

You can now delete the tracking template and hit "Save":