Walmart Gift Cards are meant for use for only purchases through Walmart Stores or online Walmart Purchases.
You can even use Walmart Gift Cards for purchasing gasoline at Walmart Gas Stations but you cannot get cash from the Walmart Gift Card at Walmart Locations.
You can however sometimes sell your Walmart Gift Cards online and get a prepaid card sent to you through mail or a check in the mail or even direct deposit into your checking account.
But other than that you cannot get cash from Walmart off your Walmart Gift Card.