You can't both have a schedule A itemized deduction and a line 10b special deduction, and the program seems rather stupid about this. It sounds like you still have a schedule A itemized deduction worksheet in the system. If you are using the desktop version, switch to Forms mode and see if you can delete schedule A and any worksheets leftover for your charitable contributions. (Each charity you enter gets a worksheet, and that information flows to schedule A.).
If using Turbotax online, you can go to the Tools menu and try deleting Schedule A, if it is listed.
If the problem is a worksheet you can't access using TT Online (because most of the worksheets are hidden to online users) you may need to call customer support and have them track down and delete the offending worksheet.
https://support.turbotax.intuit.com/contact/
