Can you use the ac recharge kit sold at walmart to recharge a window ac unit?

No. First off, the trustworthiness of any such kit sold at Walmart is questionable. Secondly, the kits are intended for automotive AC systems, and will come with R134a refrigerant... window units use a different type of refrigerant (often R22, from my understanding). Different refrigerants cannot be blended, and doing so will ultimately damage the AC unit.