to remove the tank you first remove the seat. Turn off the petcock and use pliers to slacken the spring holding the fuel line on, then remove the fuel line. Remove the single 12mm bolt at the end of the tank (normally hiding under the front of the seat). Lift the rear of the tank slightly and pull it toward the rear of the bike. As it come off you'll need to reach under the right side and disconnect the breather hose. Once it's off locate the alarm, and unplug it. There'll be some sort of bolt etc attaching the actual alarm module to the bike you'll need to undo too.
Tank replacement is a reversal of the above procedure.
