If the install appeared to complete normally, I am afraid that you need to try again. Obviously, start by uninstalling Eraser, then deleting the program folder and the Eraser 6 folder in %LOCALAPPDATA%, if they exist. Your error would be consistent with allowing the folder in %LOCALAPPDATA% to remain, but there are other possible causes and you might as well do the whole job.
Once the folders are deleted, start the Registry Editor. Certainly delete the whole of that 'Eraser 6' tree you found, but you also need to sun a search in the Registry Editor (Ctrl+F from the top, then F3 to search again), to find every reference to Eraser in the Registry. Some of them are in pretty odd places. If a key only refers to Eraser, delete it. If it seems to refer to other programs also, delete just the values that refer to Eraser. I have never had a problem doing this, but a registry backup or a recent restore point would be good to have if needed.
David