I am not sure what versions of Pro/E this is in, however in 3 and 4 at least there is a "chain end" option in the Flange feature. This allows you to offset how far the side of the flange is from either side of the edge. Depending on your intent, you may need to use a negative value.
When making more complex cuts, we unbend all, make an extrude then bend it back. Using this method you can get some very nice swept corner relief.
In Reply to Anne Rose Rivera:
Does anyone know how to work with the flange feature of sheet metal so
that I don't get additional material that I can't have on a flat?
See attached picture - the highlighted part is extra material that I