It would depend on why selling or moving. If looking to upgrade then you would want to account for how much you need for down payment and make sure with the amount you have would allow for your new mortgage payment to be acceptable to you. You dont need any equity to sell, though if you can help it usually you want enough equity to cover the closing costs and down payment for next home.
Learn what happens if you walk away from your mortgage and how foreclosure, state laws, and debt rules affect your finances—plus options before defaulting.