How to handle the outstanding balance on a bill, once the event was cancelled (and the deposit has been retained)

Here's the situation:

I work for a school, which typically has a Summer Camp program.  We engage outside people to come in once a week, and provide special enrichment activities (musical performances, storytellers, the Georgia BubbleMan (who, btw, is great!). Here's a summary of what I'm struggling with...

(I'm going to use the story teller as my example.)

In January, we booked the story teller for a performance appearance in June.

Also in January, the storyteller sent us an invoice for $235; $100 due upon receipt, with the remaining balance due on the date of the performance.

So - I entered the bill for $235 into QuickBooks, and issued a check for the $100, leaving a balance of $135.

Here's the bill:

My intent was to just let that sit there, until we got closer to the event, at which time I would cut the check for the remaining balance.  However, as you may have suspected - we have cancelled camp for the month of June.  No camp? No storyteller.

She is keeping the $100 deposit (and I don't blame her, storytellers gotta eat, too!) but now I'm left with the bill hanging around in my PAY BILLS window.

Here it is, just hanging around...

I feel like this should be the easiest, most obvious, problem to solve... and yet?  I'm totally stumped!!!!

How do I make the additional $135 go away????

Any insight/assistance on this is v v much appreciated!!!