Disconnect lines

[papacat21]

Been away from Visio for a couple of years so please forgive such a simple question. I can't remember how separate lines.  Example, using line tool I draw a simple rectangle.  The corners join and from then on it acts as an object.  Now I want to remove one line so I can make it a five sided object, like a house shape.  For the life of me I can't rememeber how.  I've played with group/ungroup, join/unjoin, snap, glue, etc.  Gotta be something simple I'm missing.  Any help appreciated.  thx

[JuneTheSecond]

It is possible in shapesheet, but easy way may be to add a point on a line with pencil tool, and to move the point.