Can I update a downloaded 1099?

If you haven't filed yet, you can go in and delete the old form, then upload the new one. If you've already filed, you'll need to Amend your return. I can provide with directions on how to do both, if you need them.

filed taxes and recently received a revised 1099. How can I download the revised 1099 and revise 1040

I have already filed.  I hesitate to download the revised 1099.  Can I delete the original 1099 even after filing a return?  I have a PDF of the original filing.  

If you already filed your return, you need to amend it to make any changes.

Wait until your return has been fully processed and you received your refund ( if you are expecting a refund ), then amend your return. 

Here's how you amend your return:

1. Sign in to your account.
2. Scroll down to Your tax return & documents , select 2019 and then Amend (change) return. 
3. Select Amend using TurboTax Online.
4. Follow the instructions, your refund or tax due will change to 0. This is normal on amended returns.

Amended return can't be e-file, you need to print it and mail it in.

Excellent.  Exactly what I needed to know.  Thank you