Thank you for your response @Carneil_C 

I tried it in a private browser, and it still does not give an option to merge. I attached a screenshot.

The one on the left is the correct account I want to keep. The one on the right is the one I need to merge into the other one. As you can see, the account types are the same, and I entered the account name exactly as the one on the left. (I tried it with and without the account number and the result is the same.) When I click "save" I get the message you see at the top of the one on the right.