Thermostats come with many different wiring methods. Most often, the wires will be held in place with a small screw. You may find it helpful to have a small Phillips head screwdriver and small regular screwdriver handy to remove the wires from the old thermostat. Some thermostats also use push in terminals which have a release button that needs to be pressed gently with a ballpoint pen or small screwdriver to release the wire. Remember to take a picture of your old wire configuration in your existing thermostat's wallplate before removing any wires. You'll need to record that configuration in your Lyric app so you know how to properly wire your Lyric thermostat.