By default, CCG3 CYPD3120 C to DP example firmware have implemented HID and you could get HID device if you have chance wire the D+/D- of Type-C to the notebook.
If you just want to disable USB flashing feature, you could try to disable below macro define.
/* Enabling flashing of the device via USB interface. */
#define FLASHING_MODE_USB_ENABLE (0u)
Thank you very much for your help.