The four hotels that you can walk to Epcot from are Beach/Yacht club, Boardwalk, Swan, and Dolphin. Swan and Dolphin are a bit of a farther walk to Epcot than are the other two. For all other hotels, you'll have to drive or take a bus/monorail.
FYI from those four hotels you can also walk to DHS, though the walk is a bit farther.