Apply a little flux to the five leads that mount to the circuit board. There are two on either side of the button and one on the back of the button. See the reference image.

Apply the Lead-Free Chip Quik Alloy to the button contacts using a soldering iron.

While the Chip Quik alloy is still in a liquid and malleable state and with carefully applied heat from the soldering iron gently slide with minimal pressure the X-ACTO knife between button and the circuit board right beneath the push button head and carefully attempt to rotate the knife blade so that it lifts the button from circuit board.

Warning: If the button doesn't slip off the board apply more heat and try to remove the button.

Warning: there are two tiny anchors the help seat the button on the circuit. You can damage these if you are not careful so don't slide your knife in the middle of the button. Slide it between the board on either side of the button. See the reference image.

Warning: there are very tiny surface mount components right next to the button. DO NOT disturb them with soldering iron. Make sure you apply heat only to the surface mount contacts on the button. DO NOT all the Chip Quik Alloy to come in contact with the other surface mount components on the board.