If your property is not zoned for smaller lots then you will have to apply for a rezone from the county and go through that process first. Once county approved then hire a surveyor and continue as suggested above.
It is possible that your lien holder would agree to release part of your property to sell if you can prove the value of your lien with less property. However, that is hard to do in today's market. They may also consider a "pay down" on your lien in exchange for releasing some acreage.
So yes, you can subdivide and sell off a portion of your property as long as you satisfy your lien holder or make an agreement with them ahead of time. Please let me know if you have any other questions. Thanks for the great question! Amy Kleefisch 928-303-1088 AmySellsKingman@gmail.com