If you have already installed your lot in your game (preferably using the Sims2 Clean installer), you have the lot listed in "lot catalog" as the last you had installed.
What I do is go into the game, and bulldoze the lot. Then I remove it from the lot bin.
That should remove any traces of the lot from your game.
I've done this many times, and it hasn't hurt the game..but I do wish more house creators would list every single EP and SP they used to make the lot, because often they do not, and it crashes my game even if I do use the Clean Installer.

The red letters at the top of this page say Do NOT Post Help Questions Here. Thread moved.

The worst that could happen is you could mess up your game. Try asking the person who made the house what EP's are needed.