If it was attached to a SO, first go into AR-N and edit the deposit to remove the SO#.
 
Then you should be able to enter it in AR-C as a negative amount and select "Reversal". Now you should have a credit and debit in your check register that can be applied against each other.
 
I can't remember exactly what happens in AR-C, but if it doesn't remove the deposit automatically, go back in to AR-C, enter a 0.00 payment and use the deposit to pay the reversal.

Thanks for the help.  I ended up doing this: went to AR-C and entered as a negative amount and reversed, then went back in to AR-C with the correct amount.  
 
On the deposit can I just select delete and it will clear it and not show up elsewhere?
 
Jere'