Seems you didn’t understand. If you uninstall the WMR Portal, you can’t use the WMR headset. In the same train, again, if you were to disable the autorun you wouldn’t be able to use the WMR headset bc it would be the same as not having the software installed, no two ways about it.
Best thing you can go for is minimizing resources the WMR Portal uses by bypassing it with SteamVR.
Edit: I also have that same headset, first days were kinda confusing bc of all the settings available. I recommend you to enable forced joystick, you’ll be able to move in any virtual setting, including movies; as well as disabling motion reprojection though this is more of a personal preference.