Customers are synced from the connected accounting system. We do our best to filter out just your customers, but sometimes there are customers/customers that you don't want to see anymore.
To disable a customer and remove them from the customers screen, navigate to the customer record, and then uncheck the "Enabled" checkbox.
Please Note, you can't disable a customer with an Active agreement. You'll need to cancel and active agreements before disabling.
Figure: Uncheck the enabled checkbox to disable a customer
This will remove the customer and their associated payments from the system, though you can find all of your disabled customers under the disabled customer tab.
Figure: The Disabled customer tab