undermine (someone's) authority

Translations
подрывать авторитет (кого-то)
The manager felt that the employee's actions were intended to undermine his authority.
Менеджер считал, что действия сотрудника были направлены на подрыв его авторитета.
Definitions
To weaken or damage someone's power, influence, or credibility, often through subtle or indirect means.