Open the reservation and click on the Accom tab shown below.

In the Accom tab, click on the amount that forms part or all of the amount you want to move.
1. Click on Corrections
2. Click on Refund

1. Click Direct Credit
2. Enter the amount of money you want to move.
3. Enter a comment if applicable.
4. Click Process.

Now go to the extras tab and receipt it there as a direct credit.