If you have not filed the return yet you can just go to My Info and delete the dependent.
If you filed your return:
If you claimed a dependent you should/could not claim you will have to wait until your tax return has been fully processed and then you can amend it to remove the dependent. You will delete the dependent in the My Info section. Do not amend until your original return has been fully processed.
How do I amend my 2019 TurboTax Online return?
https://ttlc.intuit.com/questions/2566895-what-does-it-mean-to-amend-a-return
Note: It normally takes about four months for the IRS to process an amended return. During the pandemic, the IRS has become backlogged. It is taking much longer than normal for them to process an amended return.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**