For the most part, multitasking on the iPad is a great addition, but depending on how you use your iPad, the new feature can be more of annoyance than a boon to productivity.
You can totally disable the iPad s multitasking under Settings General Multitasking.
Set the Allow Multiple Apps toggle to off.
This will disable both Slide Over and and Split Screen mode.
Obviously this isn t useful for everyone, but if you don t use Slide Over and find it annoying to accidentally pull it up, at least there s a way to disable it.
How to Disable the Slide Over Sidebar on iPad OS X Daily