There are two scenarios:
1. You have a PRS counter ticket. In this case, if the ticket remains WL after chart preparation, you can cancel it at reservation counter and get full refund. By rule you cannot travel on this ticket. But if you ask TTE before boarding the train and he agrees, you can travel. He can give you a seat if any available after the journey starts.
2. In case it is eticket, and remains WL after chart preparation, it gets cancelled automatically. You cannot travel on such ticket.
Note:...
more... Above explanation is for fully WL ticket and not partially confirmed ticket.