I have office collect customers on a route that are being invoiced by ProCarrier. How can I configure ProCarrier so carrier collect customers are invoiced while office collect customers are not invoiced?

Remember you can setup as many rate codes as you need. Assume all these customers have the same delivery schedule and are billed at the Daily rate. Make two rate codes to manage these two different situations:
 
Daily - Carrier Collect - DAY-CC
Daily - Office Collect - DAY-OC
 
Setup the Daily Carrier Collect rate code. Edit this rate code by checking off the appropriate delivery days and enter the correct billing amounts. You are telling ProCarrier the delivery days and delivery charges for customers with this rate code. These customers are invoiced.
 
Next setup a new rate code called Daily Office Collect. Check the appropriate delivery days for this rate code, however, enter $0.00 for all billing amounts. You are telling ProCarrier the delivery days for these customers and the delivery charge which in this case is $0.00. These customers will appear on the delivery list as they should, however, they are never charged for these deliveries by ProCarrier and these customers are not invoiced.