Split screen email while in full screen

When watching something in full screen mode and you open an email and it does the split screen, how do you get the email to go away? You can drag the split to make both sides different sizes, but I didn’t see an option to close the email and make my show full screen again. Had to exit full screen mode and that did the trick, but then I had to enter full screen mode again. Not that big a deal I guess, but it just seems that there should be an easy way to close the message and not leave full screen mode. If there is, I guess I just missed it. Thanks in advance!