If you haven't already filed, you will have to delete the form (e.g. W-2, 1099-MISC) that has the typo and re-enter it in the appropriate interview.
If you have filed, you will have to wait until the IRS accepts or rejects the return. If they reject it, you can correct it and resubmit.
If they accept the return, you can amend it when amendment forms are available. Otherwise, you may get a letter from the IRS asking for additional information or explanation.
See: How
do I delete forms in TurboTax Online?
Why does this happen? Once you enter (or import
or transfer) certain information, the program creates or updates forms and
worksheets that use that information. In many cases, you cannot
"change" that information in the interview process - in a manner of
speaking, it has been "written in ink" on the forms. You have to
delete the form and any associated worksheets in order to correct.