Removing "NONE" as an option for supporting

Is there a way to remove the NONE option when adding donation amounts?

if you look here:
http://www.walkforwoundedwarriors.com/

I only have 30 dollars set up as a prize not sure where the NONE is coming from, yet there it is. Frankly thats sort of stupid to have that there if they aren't donating they aren't supporting.