How to remove elements on the touchscreen?

I’m new to Hestiapi / Raspberry / Linux and hope someone can help me with basic issues.
I have assembled the Hestiapi Touch version with 4 relays. After some trouble with the SD card flashing, it seems to be working. I can connect with SSH, and openhab works on Iphone and PC.
My plan is to use HestiaPi as a thermostat only for underfloor heating. I therefore want to remove unwanted elements on the touch screen. How can this be done?
Furthermore, the BME sensor must be replaced with an infrared temperature sensor MLX90614. This may be too ambitious for my knowledge, but maybe it can be possible with a little help?
The purpose is to be able to control underfloor heating by measuring the surface temperature.