This video #3 of 7 shows how to remove the window trim.
This 6 minute total series of 7 short videos shows you how to remove and replace a broken window appliqué / trim for a 2015 or later GM (Yukon, Tahoe). I broke the video into 7 short pieces to focus on the key steps.
Here’s a link where I purchased my parts (refine results to select for your year, make, model): https://www.gmpartsdirect.com/search?search_str=applique
do you have the part number on the trim you are changing or can you link the site to purchase from?