Troy, both Don and Durenda hit the nail on the head... Durenda is talking about a "partial release of mortgage" that will except out the lot that you want to sell off. You will need to do that before you can sell it. But you got a lot to do with regards to zoning and subdividing as Don was talking about first.

your lender would need to release that acre from your mortgage. You may want to speak with your lender about whether or not they will do that. If they will, find out from them what they requie.

Best of Luck

Check with a real estate lawyer. I'm not a lawyer, so this isn't legal advice. However:

It's not likely you can accomplish what you want with a quit claim deed. A quit claim deed relinquishes any right you have in a property. What you want to do is subdivide the property. And that likely involves an application and approval process with the appropriate city or county. And there likely are a bunch of regulations you have to comply with--access to transportation, for instance, so that the property isn't landlocked. If the property has/needs a well or septic, you may need the well dug or the land perced. There may be a minimum size of lot required, especially if it's on well or septic. And on and on.

Again, get a good real estate lawyer. Tip: Get one who has good connections with the licensing county or city. A current or former mayor or town councilman would be good. A lot of zoning decisions are made not just on the facts, but on personal connections, too.

Hope that helps.