If you need to correct a dependents Information prior to submitting your Return, you can do so in the Personal Info section of TurboTax Timeline.

Once there, you can edit the Dependent section to reflect the correct information. There is either an EDIT or DELETE button to ensure you make the adjustment correctly. Turbo Tax Saves all entries as you go along so it will automatically save the correction once made, so you can File successfully. If you tried the edit button without success, try deleting and re-adding the information back in..

If you have already Filed...(see below)

Please note that if you have already filed your return, you must wait until the return has been Accepted or Rejected in order to take the appropriate steps. If Rejected, you can simply correct this error and any other reason the return was rejected, then e-file. If your return is Accepted, however, you will need to Amend your return in order to file a correction and mail that printed return in. 

Hope this Information Helps!