It is a Murray Eliminator, made by Murray, but possibly sold as a Murray bike, or through a department store or auto parts store back in the late 1960's or early 1970's. The frames are all stamped with a serial number on the non-drive side rear dropout. It will have a code for the year, a code for the place it was sold, and the model number.
If you post the serial number I think we can find the year and place it was sold. You may have to do a little sanding to see it though!