We can do this by editing the payment
  1. Click Revenue > Transaction Search
  2. Search for and select the transaction
  3. Click edit payment in the upper left hand corner of the screen
  4. Remove the application by clicking on the item under current applications and then click remove User-added image
  5. Change the application drop down to pledge and click the add button to add the payment User-added image
  6. Choose how you want to apply the payment to the pledge and click OK
  7. Click save to save the payment
If the payment has been deposited and the deposit is currently locked you may need to follow the steps in this article to unlock that deposit before following these steps