Inform the supervisor is an appropriate action to stop sexual harassment.
Employers are responsible in providing their employees a work place that is discrimination and harassment free. They are required by law to take steps to prevent and deal with harassment in the workplace.
Because supervisors and managers represent the employers in the departments, they are tasked to ensure that harassment does not incur in their specific departments. In the event that harassment does occur, then they should be informed and proper steps should be implemented to stop the harassment and ensure that it will not happen again within the company.