Go to Operations > City Ledger and locate the invoice with the charge you wish to transfer. Proceed to the appropriate tab where the charge is located (either the Transferred tab if the charge was transferred from the Guest Folio, or the Charges tab if the charge was posted to the invoice after it was created).
In this example, the charge to be transferred is located in the Charges tab of the Details for Invoice screen.
Ensure the black arrow is pointing towards the charge that you wish to transfer and select the Transfer button located at the bottom of the screen.