I was able to disable it. Edit gcode_macro.cfg (the right one in /usr/data/printer_data/config) and add :
[gcode_macro CX_NOZZLE_CLEAR]
rename_existing: CX_NOZZLE_CLEAR_PY
gcode:
# NOP
[gcode_macro NOZZLE_CLEAR]
rename_existing: NOZZLE_CLEAR_PY
gcode:
# NOP