The best way to handle an incompetent employee is to first help him grow. Help him with the basic materials necessary to become a better employee. You can help him with paid courses. You can sponsor his trainings.My father's usually comes home to complain of an Incompetent employee, that doesn't put in much hours in the job. The employee was recently promoted to head of a department, so he feels that he can slack off because he now heads the department, and he can't be easily laid off because he's an important figure in the business who has brought much clients to the company.
How can one make him to drop his lax ways and become diligent once again.