Analyse the overall situation
First of all, check all the details related to the employee. Why is he/she not working properly? Is there any personal issue with him/her? These things can contribute to a lot of stress, so make sure that you keep them in account. Once you have done that, analyse the offense made by the employee, so that you can reprimand him/her accordingly.
Write down all the details
While analysing the overall situation, note down the points, which are important. This will help you understand the problem in a better way and you can address the employee in a constructive manner.
Call for a private meeting
Whenever there is a serious problem, don’t make it public to the rest of the employees. Call in a private meeting with the troubled employee and talk to him/her about the overall situation. If you make the details public, the employee will feel bad and will despise you.
Keeping a positive attitude is always important in all departments of life. No matter you are superior or not, it is better to be constructive. Therefore, never try to insult the employee in front of others, just because you have the authority of doing so. Even when you are scolding him/her, keep mentioning the good points, indicating that you expect the best in the future.