The seat cut-off switch on a riding lawn mower is designed to kill the engine if someone falls off of the seat of a riding mower and to keep the engine from starting at all unless someone (or an appropriate amount of weight) is in the lawn mower's seat. This switch is a safety feature; consider carefully before disabling this feature.
Lift the lawn mower's seat. In some cases, the seat will simply lift up (hinged on one side), but in some cases there may be a latch that will need to be released before the seat will swing up.
Locate a small box with two wires leading into it under the seat. Cut both wires at the point where they enter the small box.
Strip approximately 1 inch of insulation off of the end of each of the two wires you just cut.
Twist the two ends of bare wire tightly together and wrap them in electrical tape.
Lower the seat and test the lawnmower by attempting to start it with no one in the seat. Make sure the lawnmower is in "neutral" when you attempt to start it. If the mower fails to start, check the connection you just made.