Does a secured debt ever become an unsecured debt?

A secured debt can become an unsecured debt if the underlying collateral is surrendered, such as in a foreclosure or a repossession. In foreclosures and repossessions, the collateral is often sold for less than you owed on it, in which case you may be liable for the deficiency even though you no longer have the underlying collateral. That liability would then be an unsecured debt.