what is the tax reason you're asking?  but if you didn't pay any the number would be ZERO

It wants amount. It won’t take 0

If this is a state interview question then back up and indicate you do not have entries for this credit. 

There is no reason TurboTax(TT) would be asking that question, in the Federal Section.

 Some  states have a Renter's Credit.  As Critter -3 suggested, you don't qualify (since you don't pay rent), so you should not have entered that section of the state program.  

How to get out of that section will depend on which state it is.  Usually, it's on the screen  titled "A few things before we wrap up your state taxes"  or Other tax Situations at the Summary Screen.