I believe you can - and at the same time, you can pursue a grievance even if you have left, although it may become more difficult and may be an obstacle to your moving on psychologically.
Think about what you want out of the situation, and find out what outcome has resulted from other similar grievances in your organisation.
In many cases winning a grievance does not result in much - a line manager might be told thay have been very naughty and not to do it again. If you intend staying put, it is important to see the grievance through to flag up that there is a problem that needs properly sorting out.