I need to remove my ex husband from my account and file by myself, How do I do this?

Start a new account with a new user ID.  If you continue to use an old account that has been used for past joint returns, the embedded "spouse stuff" will trigger errors as you prepare your return.

https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-start-another-return-in-turbotax-online/00/25596

You will need to create a new account with a new User ID since you are no longer married. 

Removing your ex spouse's information is not reliable on the current account.

Go to this TurboTax website and click on Sign up to start a new account - https://turbotax.intuit.com/personal-taxes/online/file-your-own-taxes/