I need to update my banking info for direct deposit. How do I do this. I have not yet filed and most likely won't file a 2020 return.

If you are not going to file a 2020 return are you asking about 2019?  Did you file 2019 yet?  You have to print and mail 2019. If you need to change 2019 return you need to use the Desktop program now.

How to finish a prior year online return   

https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-finish-a-prior-year-return-that-i-started-in-turbotax-online/00/26322

Or since you have to print and mail 2019 I suppose you could just hand write in the right Direct Deposit info on your 1040.

Or why do you need to change the Direct Deposit Info?

If you are not going to file a 2020 return you have no way through TurboTax to give new banking information to the IRS for a stimulus check if that is why you want to change it.   TurboTax lets you enter bank information when you file a tax return.  You cannot change it after you file.  So if you entered direct deposit information using TT for a 2019 return, but will not be filing a 2020 return, you cannot change your bank information on the TT site.  Wait and see if the IRS gives you a way to change bank information if Congress ever passes a second stimulus bill.

This is exactly what I needed to know. Thank you!