How do I disconnect a IBS-TH2 off the Wi-Fi gateway

I am wondering if anyone can help? I am struggling to disconnect the IBS-TH2 off the Wi-Fi gateway.

May I know your gateway is IBS-M1 or IBS-M2?
If it is IBS-M1, is its INKBIRD logo gray or blue?

The gateway is a m2 gateway

Please access the settings of the IBS-M2 via the INKBIRD app. Please select the sensor you wish to disconnect and remove it.

This is what I am getting when logging in to the app

The screenshot shows that it is the IBS-M1 first generation. It does not have the option to delete one of the sensors individually.
Please back up the historical data of the sensors first.
Please remove the batteries of the IBS-TH2 which you do not want to use.
Please press and hold the reset button on the side of the IBS-M1 body, it will delete all the sensors, then reconnect the sensors you need to use.