If an academic employee desires to terminate an existing appointment or to decline a reappointment, the employee shall give notice not less than three months if the employee's rank is instructor or assistant professor, and not less than four months if the employee's rank is higher, before the end of his or her duties during the academic year exclusive of a special session; but the employee may properly request a waiver of this requirement in case of hardship or in a situation where he or she would otherwise be denied substantial professional advancement.