Getting rid of split screen on my iPad Pro

Good morning. I am trying to get rid of the split screen in email on my pro. I tried to move the line between the email list and the body of the email but it doesn’t move. I tried to follow instructions when I googled it as I’d like to get rid of it permanently but I can’t find the path that they take after “settings”. Sorry but I’m hopeless on this stuff. Thanks for any help that you can give me