TurboTax Federal review is asking me to check tax withholding information for my Form W-2G or Schedule K-1 but I have neither. I am retired.. What should I do ?

Please look through your forms and delete W-2G and Schedule K-1 if you see any. If this does not remedy the error, please continue the question, and provide any additional information that might be useful, such as the TurboTax program you are using, Desktop or Online? What income documents did you enter? 

For Desktop, switch to FORMS from STEP-BY-STEP on the top right. 

HERE is how to view and delete forms using Online