How to remove Payment Plan Fee

Hello,

There is a need to remove a $33 installment payment plan fee from a group of student accounts. I know that if the payment plan is cancelled, then the fee is removed.

However, these students need to remain on the payment plan and have just the fee removed. Any suggestions on how to accomplish this? Usually, I can use pop-select - for instance, to reverse a $25 late registration fee (which is t-calced on), but there does not seem to be an option for the installment fee. 

Thanks!

Andrea