Is there a way to disable the phone display waking up when I touch the fingerprint sensor. I mean I don't even have a fingerprint set up and I don't want to use it. The phone is Redmi note 9 running on Miui 13.
Just to be clear, you do not have this biometric lock feature enabled, but you want to be able to touch the button but not have the phone respond? Why are you touching the button if not to wake the device?
Initially I thought this was an in-screen sensor but my search revealed that this is a button and I believe unfortunately that pressing buttons will always indicate to the device to wake, even if only to report a failed log-in event. This seems to be one of those situations where you tell the doctor, it hurts when I do this and they reply, then don't do that. If you don't want the screen to wake don't press/touch the button.
Although it doesn't sound like it, if you're asking how to remove your fingerprint I found this video which talks about lock methods which includes removing your fingerprint.
Again it doesn't sound like that is what you're asking but perhaps if you talk to us about why you're touching the sensor and not wanting the device to wake we could help with that. Is the device waking in your pocket, do you pull your device out and find the screen on and feel this is running your battery down, are you accidentally touching it while it is your pocket or a bag? What is going on?