To answer your question simply : Yes, it can be sold.
But as the other two responders have noted
1- If a lease is in place, you may be obliged to honor it.
2- Best advice once you are in contract, is to discuss this with your attorney.
Ultimately, a compromise may be the solution, but without knowing
exactly what is written in the contract it is hard to say.
If they guaranteed the house vacant, they may be obliged to do so.
However, if the tenant did not move because they did not find something, you may have a choice.
You may be able to close with the tenant and get a reduction in price-
but then you are taking on the responsibility of the tenant yourself.
Ultimately, as said before, check with your attorney for options.
If you are not in contract and this was a general question, maybe I can help.
I am a licensed broker associate in your town of Middle Village in Queens.
Feel free to contact me and discuss in further detail or to help you find a house that is vacant.
Robert Hoffmann, 917 453 0207