In this attachment you'll see 2 flanges. I have to remove them to be able to fold out the part. I removed one flange using "Delete Face". But somehow I have to use the Heal option because it becomes like a shell when I just use delete face. I've tried using "Patch" and "Stitch" but that didn't do any good. I tried using "Delete Face" at the small transitional radius before the flange and then removing the rest of the flange but that didn't work either. I'm out of ideas.