A customer can be deleted from the system, provided that the customer does not have transaction records in the system.
1) Go to Setup>>Customers.
2) Go to the Actions column for a particular customer ( you can also use the filters to search).
3) Click on the drop-down menu "More Actions" and click on Delete.
4) The system will ask you for a confirmation
5) The next confirmation message will appear at the lower right of the screen: