How to disable Cardboard Vr when a game starts and activate it later

I created an Ue4 cardboard Vr game for Android and I want to make a Menu, which is not in Vr. I tried to master this by disabling HMD-Settings when the game is launched. This works, but when I start the game there is a momentum where Vr is enabled. How can I set Vr off by Default and be able to enable it later. I think the solution is in the source code but I can’t find it. Thanks for replying!