The warning that gmail is no longer available is making it difficult to use my email. I want that folder remove soonest
If you log into your email on the web site, you should be able to remove the folder.
Where is it you're seeing that 'gmail' message? On what device, what email app? Did you have a gmail email account added to your email client? Can you delete/remove that email account?
A private message like this does not assist other users that may be looking for the same answer.