How can I turn off Multi tabs and screen splitting on ipad with ios 16.6?

Hello Ladderback77,

Thanks for using the Apple Support Communities!

Currently there isn't a way to completely disable this option on your device. If you'd like to see that added in the future, you can submit that feedback here: Product Feedback - Apple

If you'd like to close out of the side by side view, the steps in the "Make adjustments to multitasking windows" section of this article can help with that: Use multitasking on your iPad - Apple Support

Cheers!

Unlike iPadOS14 and earlier versions, multi-tasking (including split-view and slide-over views) cannot be disabled from settings. Multi-tasking has received a significant overhaul with iPadOS15/16, both simplifying its use and introducing new controls. 

Key to accessing and controlling (or completely avoiding) multi-tasking is the small “three-dot” multitasking button that is found at the top-centre edge of the visible App windows. 

Information and guidance for using multi-tasking can be found in this support page:

Use multitasking on your iPad - Apple Support

The iPad User Guide is a rich source of frequently overlooked information about your iPad and iPadOS. The Guide is available both online using a web browser (such as Safari), or as an Apple Books download:

iPad User Guide - Apple Support

https://books.apple.com/book/id1567104892

The Tips App, installed by default on all new models of iPad, provides a brief introduction - and leads you to the User Guide. In case you missed it, here is a link to the Tips App:

https://apps.apple.com/gb/app/tips/id1069509450

Apple also has a huge YouTube Channel - containing videos and feature guidance:

https://www.youtube.com/user/Apple