You don’t need to remove the existing devices. You can (a) add your new controller to the existing network/controller, thus making it a secondary controller on the same network - this copies all your devices over the new controller - and then (b) use the “controller shift” function to make the newly added controller the primary controller - see the thread Z-Wave Stick Migration (via Z-Wave "Controller Shift" feature).
I have recently migrated from a Zwave.me stick to an Aeotec stick.