Using the TurboTax desktop editions, in the File section just select E-file. On the following screen select Do not e-file my federal return.
Using the TurboTax online editions see this TurboTax support FAQ for e-filing the state tax return after the federal tax return has been e-filed - https://ttlc.intuit.com/community/e-file/help/how-do-i-e-file-my-state-after-i-already-filed-my-fede...
