To delete an account - click account settings - highlight the account to delete - slightly below is 'Account Actions' menu, which as option to remove account.

If I delete the account, it deletes both copies. I only need 1 copy deleted. I did see in my program files, that there are 2 entries for Thunderbird, so I am going to try to delete one from there. I should be able to reload it if it does not work.

So, the 2 profiles, one is old thunderbird and the other is beta. Still need to know how to get the duplicate email account not to show up. The 2 accounts have exactly the same emails. When I delete an email in one, it deletes in the duplicated one.