Process: If you click on the tick next to the amount and then on the Process button, the status will be changed to Payment Pending. it will be shown in orange and will be recognized as a debt to the customer. 

Omit: If you click on the tick next to the amount and then on the Omit button, the fee will disappear and instead you will see some lines appear which confirm the payment is not active. To activate the payment again, click on the lines. 

Edit: If you click on the tick next to the amount and then on the Edit button, another field will open where you can change the fee.