I am continuing to fight with this imported surfacing project. I have an imported surface model of a fiberglass part. I am currently attempting to remove the trim flange on the outer edge of the part as shown below.

Weather I select one face or the whole outer flange and attempt to delete it I recieve rebuild errors that this would create a vertex with more than two converging open edges. I have selected several different faces to delete with the same results. Can someone explane this to me so i have a better idea of how to solve this problem?

thank you

Jim