Turn off power to the HVAC system at the breaker
Remove the Nest display from the base by pulling it straight off
Label the wires before disconnecting them
Loosen the terminal screws
Remove each wire from the terminals
Unscrew the Nest base from the wall
Remove any wall plate or trim if installed
Cap or tape the exposed wires so they do not touch
Restore power only after the new thermostat is installed or the wires are safely secured