It is asking about your previous contributions (new money that yiu contributed yourself - not earnings) that have not been previously withdrawn . That can never be a negative number. The reason for the question is that you can always remove your own contributions both tax and penalty free.
However, if this is a qualified distribution (code Q) in box 7, or you are over age 59 1/2 then it is tax and penalty free anyway so it really does not matter what you enter or 0 or leave it blank.
TurboTax just blindly asks that question without regard to the box 7 code or your age.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
