Choose which Payment types are accepted in your hotel - later on you will be choosing one of these payment types when charging a reservation. 

You select what type of payment the guest is using from the drop down list (this is for all charges that are not charged through a payment gateway)  

To disable some of the pre set up payment type, click on the pencil icon and then untick "active" and save.

You can select the payment type on the reservation card under Payments.