Impeachment is a legal process through which a government official can be terminated for gross negligence or some other dereliction of duty.
When a public representative is elected to an office, it is a job but not regulated by normal employment legislation. However, the understanding remains that there may be a need to remove a person who was elected to a post if they show themselves incapable of working properly, or if they do not have the expected skills or level of ethics that are required to continue in the role.
There is a set process that must be followed when an impeachment takes place. An impeachment can also only take place under certain circumstances, which are dictated by regulation. If an impeachment process is started, the articles of impeachment will be followed to conclusion.