Regarding terms/tenure of principal appointed in school as a employee with salary grade as CBSE Pvt

Respect sir/madam, I am working in CBSE private school since 8 years and I have found previously appointed principal's were termed/tenured duties with fixed 4.5 year. But since last 7 years experiencing that the principal appointed the school has taken school's fully incharge even though she is appointed as staff and paid as staff but she behaves like Owner, she tries every chance by forcely or by emotional strategy to convey change in rules as per her desire. I have noticed that she have started harassing staff who ever tries to complaint against her to the management and even keeps her secret contact with management's family so that she can collect those names of staff personally who tries to reach management without her acknowledgement and then puts the staffs in trouble and than proves the staff is misinterpreting the information about her and is untrustworthy and issue memo of wrong doing. So that the staffs get afraid of complaining to management ever again and suffer and let things happen as it is going like her desire. There are many incidents and work doing of her that I can't put it all in words right now. So please kindly give me information regarding principal's terms/tenure fixed by CBSE school act for private school were principal is appointed as staff and school has to change or terminate after the tenure ends. Please let me know any leads for the information so that I can contact regarding this matter to DEO or CBSE private school judicial complaint.