Open up a command prompt with administrator privilages, either right click and Run as Administrator, or hit the Windows Key type in cmd and then hit CTRL+Shift+Enter.

Sometime you may need to turn it on so you can install a modded driver or something, other times it needs to be turned off so you can install EasyAntiCheat…

Turn On

bcdedit -set TESTSIGNING ON
bcdedit -set NOINTEGRITYCHECKS ON

Turn Off

bcdedit -set TESTSIGNING OFF
bcdedit -set NOINTEGRITYCHECKS OFF

Reboot for the changes to take effect