Removing gas tank

The best option would be to remove the lines and the selector assembly and attach the fuel and return line from the rear tank to the engine feed lines. Then you do not have to worry about leaks or running issues.

But be sure you want to remove the front tank. A new tank is around seventy five dollars and unless the rear tank has been replaced it could start leaking as well. You could install the new tank and delete the rear tank lines and not worry about it for a long time.