Ok if you had a house and then placed a second one and demolished the first one that was now condemned, you will be on a timer even if you demolish the second house. The proper order to stay off the timer means you must drop every house you have before you place a new house.
Now if this is the only house you had on that account, and you placed it and now wish to demolish it you will be fine. If you can't demolish it it is because you have vendors up or you have items in the moving crate. Empty the crate and you should be able to drop it and place a new house.