You cannot delete an employee account that has dependencies in other portal modules. You will have to first remove the dependencies, and then  delete the employee account. However, there are certain dependencies that cannot be removed. For example, if the employee has approved payslips. In such cases, the employee account cannot be deleted.

1. At the top of your dashboard, click the module access icon > Administration > User to open the Manage Users page.

2. Search for the user and when you find the employee, click on the employee’s name. Basic details of the employee’s profile is displayed.

3. Click the View Profile button to view the employee’s complete profile.

4. In the top right, click the Delete button.

The Remove employee page is displayed.

5. Select one of the options.

If you want to archive the employee account, select the Employee leaving the institution option. You must specify the reason for the employee leaving, and then click the Delete button.

If you want to permanently delete the employee account, select the Remove employee records option. A confirmation message is displayed. Click OK to confirm removal.

NOTE:

Also to note the point that deletion of the employee can be restricted if there is any dependency existing for the employee. The dependencies can be cross verified in the below points. 

• Any Payslip( generated or approved) present for the user
• Any Subject association for the user
• Any finance transaction
• Any timetable entries
• Any employee attendances
• Any timetable swaps
• Any plugin association ( discipline, task, discussion, blog) 

For more you can watch this.