I used the command to "fit walls to objects" and the walls properly extend up to the next object (ROOF).  HOWEVER, sometimes I make a mistake, and I want to "un-do" it.  I find that I select the wall, but in the OIP there is no field to correct the extension.  I adjust the 'top bound' to a ceiling or roof, but the wall retains the height it generated after I used "fit walls to objects".  i can manually delete vertexes in the walls, but I still end up with a wall that is not the correct height fo