You can disable DirectVR with a hotkey temporarily in such cases (default ALT+B),
The menu option is on the DirectVR page of the menu, you can flip between pages with the arrow buttons in the top/left corner of the menu or the shoulder buttons on your gamepad/motion controllers.
You don’t really want to disable DirectVR for good though. If available for a game, DirectVR modules improve the experience a lot, e.g. by enabling better head tracking, automatic FOV setup and so on. Use the temporary hotkey switch instead if necessary.
BTW1: Many hotkeys can be used in two ways: either with “hold/release” if you only need the function for a few secs. Or with short keypresses for toggling the according function on/off.
BTW2: A list of useful hotkeys (including a way to change them to your liking) can be found in the config app.