Line 12b on the "Line 12 Excess Employer Contributions and/or HSA Funding Distributions Smart Wksht" is reporting the amount of excess contributions that you agreed to withdraw after December 31, 2018 and before the due date of the return. It is not asking you to remove it again.
Line 12a should be the $3,450, line 12b should be the $3,450, and line 12c should be zero.
Ah, perhaps you mean that you are in the federal review, and you are getting an error on line 12b. I don't know why since if you entered everything correctly, there should be a number there.
However, we at AnswerXchange cannot see your tax return nor the screen you are on, so we would have to play "20 Questions" to get to the root of the issue.
It will probably be faster to do the following if you are getting an error in the federal review: Delete all the HSA information and re-add it, which will cause the excess contribution error message again and allow you to re-enter the amount you are going to withdraw (because you already have).
1. make a copy of your W-2(s) (if you don't have the paper copies)
2. delete your W-2(s) (use the garbage can icon next to the W-2(s) on the Income screen
*** Desktop***
3. go to View (at the top), choose Forms, and select the desired form. Note the Delete Form button at the bottom of the screen.
*** Online ***
3. go to Tax Tools (on the left), and navigate to Tools->Delete a form
4. delete form(s) 1099-SA (if one), 8889-T, and 8889-S (if one)
5. go back and re-add your W-2(s), preferably adding them manually
6. go back and redo the entire HSA interview.
