OK - in that case I’d rather try to use ground shielded wiring to connect the touch sensor.
Disabling the touch sensor could be done by installing a microswitch as Z-endstop to the gantry & connecting it to the mainboard “Z1-” port (PE1) & changing the firmware as follows:
Comment out BLTOUCH PROBE in file “Configuration.h” :
//#define BLTOUCH
After firmware build & installation it should work as desired. If not check that Z-endstop switches with COM to ground and NC. Otherwise toggle in file “Configuration.h”:
#define Z_MIN_ENDSTOP_INVERTING true