The Internet Bridge and Smart Radiator Thermostats can be simply disconnected before installing tado° X devices.
For wiring instructions to replace a Wired Smart Thermostat (V2/V3/V3+) with a Wired Smart Thermostat X, go to the tado° app and follow these steps:
Go to Settings > Rooms & Devices.
Select Add device and scan the QR code of your tado° Smart Thermostat X.
Select Installation Instructions.
Select the blue button Select room thermostat model.
Enter 'tado thermostat' into the search field.
Select Wired Smart Thermostat V3+ to access the instructions.