This isn't your fault, but I'm REALLY tired of answering this question.
You'll have to clear the AP requirement for a level for it to not have that level. The current WallMarket is bugged and will not accept a blank value. You'll have to give it a requirement of 65535 to blank it out. Completely my fault.
So if you want it to have three levels, make level 4 and 5 blank.