I think the only way to zero out minutes or a start is to offer a redshirt. You can promise LOWER minutes (if you offered MORE than 10) .. but there is no zero in there .. 10 is the lowest. Doing that (going from 15 or 20 down to 10) is a major it in effort.
Doing a redshirt has negative impact and it SHOULD also remove promises .. but it would have a very negative impact on the effort to the recruit.
Based on the beta forums, I don't know for a fact what exactly they did WRT redshirts and promises. See these links. May chapel knows more about that:
Link1
Link2