Can you sell a used ATV without a title?

Essentially, no. All states require either a valid title or lien release certificate to effectively transfer legal ownership to the buyer. Even if the buyer lives in the sticks and buys the ATV knowing there is an entity which has a lien on the vehicle, he could be found guilty of colluding with the seller by completing a transaction with the intent to defraud the lien holder out of their property. In some states, after the lien holder obtains judgment against the seller, the seller may be ordered by the court to fill out an order for disclosure and if that ofd is not filled out lawfully and truthfully, the lien holder could then argue that the seller sold the vehicle with either the intent to defraud the lien holder or through gross negligence (if they claim they didn't know they couldn't do that). Not to mention the tax implications of not reporting the sale of a vehicle which is supposed to be registered.