I created a sketch on a part in context of the upper assembly, and it created the references to the assembly. Now I want to break the references and independently dimension the sketch in the part. I did the "List External Refs" and broke all. But now in the part sketch it still shows the relations and all of the lines are essentially fixed. Is there an easy way to get rid of all those broken relations without having to select them one at a time and delete them?

I recently had a similar situation where somehow when I opened the part later all of the relations were gone and the lines were unconstrained. I don't know how it happened with that other part.

I know I can change my system settings and prevent it from making the relations in the first place, but that doesn't help me if I want the relations there for a while and later choose to get rid of them.