Locate the main electrical panel in the home and switch off the breaker for the doorbell circuit.
Remove the screws that hold the doorbell switch to the outside wall, using the appropriate screwdriver. With the switch removed, the terminals in the back of the switch will be exposed.
Test the two switch wires using a voltage tester. No indicated voltage on the tester verifies that the power is off and it is safe to continue.
Loosen the two terminal screws by turning each one counterclockwise with a screwdriver.
Remove the wires from the switch.
Connect the wires to the terminals of a new doorbell switch. Tighten the terminal screws clockwise.
Install the new switch onto the outer wall. Tighten the mounting screws with a screwdriver.
Restore power to the doorbell and test.