how do I delete my state return and just file federal return after I've already paid for but not filed my state return?

Once the TurboTax account fees have been paid you cannot delete the state tax return.

You will have to contact TurboTax support for assistance with this problem. Use the key words Billing Issue

See this TurboTax support FAQ for contacting support - https://ttlc.intuit.com/turbotax-support/en-us/help-article/account-management/turbotax-phone-number/L0Od33nMQ_US_en_US?uid=lfgviwbm

Support can also be reached by messaging them on these pages https://www.facebook.com/turbotax/ and https://twitter.com/TeamTurboTax

To delete your State Tax Return in TurboTax Online, please follow these steps:

1. Sign in to TurboTax and choose Continue or Pick up where you left off
2. On the left side bar, choose State Taxes and then Your State Returns
3. Click the trash can next to the State that you wish to Delete
4. Choose the blue Delete box to finalize your decision