Relegate means "to assign to a lower position." If the quarterback of the football team stops making decent throws, he might be relegated to the position of benchwarmer.
Relegate rhymes with delegate — both words derive from the Latin legare, "to send." Relegate means to send someone down in rank. Delegate means to send someone in your place to complete a task. In the workplace, managers who can't figure out how to delegate may get relegated to a lesser rank.