Disconnect the Kenmore dryer from the wall outlet. Wear safety glasses.
Locate the door switch. It is around the door opening in the front panel. You may be able to pop the switch out of place or you can remove it by removing the screw.
Label the two wires leading to the door switch so that you will be able to properly re-attach them later. Use a pair of needle nose pliers to carefully remove each wire.
Pull the switch out from inside the dryer cabinet.
Insert the replacement switch into the dryer cabinet as instructed on the product label. Re-assemble the dryer cabinet, if necessary. Test run the dryer to make sure it is functioning properly.