How Do I Close Open Websites on iPad 10?

Here is how to: Close an app on your iPhone or iPod touch - Apple Support

The swipe has to be from the bottom and upward slowly.

The following controls might interest, too: Access Control Center on your iPhone - Apple Support

For more info: iPad User Guide - Apple Support

Joey C 2 wrote:

Thanks! Really? I thought for iPhone and iPad out was advisable not to have too many apps open in the background. Maybe that is wrong, or is not the case anymore?

It was never the case.

Apple would prefer that no one need to fuss with their apps, and has worked toward that goal; to make an iPhone or iPad self-managing to the extent feasible.

More reading, with citations: Do not close iPhone and iPad 'background'… - Apple Community

Joey C 2 wrote:

I tried swiping up from the bottom of the screen to show all open websites and apps, but that only seems to work about 25% of the time.

You just need to get the hang of it. Swipe up slowly and let go about halfway up the screen.

Bottom center upwards, slowly, about a third to a half the display, and stop and hold until the display shifts, let off from the hold, and the grid of running apps should appear.

Apple generally doesn’t suggest quitting apps either, absent some issue with the app itself.