To depose; to forcibly relieve a monarch of the monarchy.
To remove any governing authority from power.
To remove from any position of high status or power.
1753, Arthur Murphy, The Gray’s Inn Journal, No. 23, 24 March, 1753, Volume 1, London: P. Vaillant, 1756, p. 168,
[…] we conclude, sincerely wishing, that you may continue to display your usual Graces of Elocution, and admirable Powers of Action, untill Harlequin shall dethrone the great Shakespear, or Pierot usurp the Seat of Johnson.
(figuratively) To remove (something) from a position of power or paramount importance.