I started filing my taxes individually but then my husband filed for us jointly. I keep getting notices that I need to finish filing. How do I delete the other filing?

That's just the marketing dept. They don't know you filed Joint. You must have your own account from before. Just ignore the emails.  You can't delete accounts.  Just ignore your old account.  

You don't have to delete the other tax return that you started. It won't go anywhere. Nothing will happen with it if you just leave it alone.