I don’t like the split screen. How do I get rid of it?

Those links also contain instructions on "not how to use it."

Turn Multitasking features on or off

To leave Split View, touch and hold, then tap Merge All Windows or Close All [number] Tabs. You can also tap  to close tabs individually.

Just swipe up from the bottom of the display to close Safari. Review: 16 gestures that will make you love using your iPad

Review: Use Multitasking on your iPad - Apple Support, and How to split screen in Safari on your iPad - Apple Support for using "split screen."