If the King does not abdicate, he will have to be dethroned.
Examples of dethrone
dethrone
On the other hand it's nicely corrective to dethrone the usually deified cortex.
From the blogs.psychcentral.com
With all due respect a 2nd BCC win may not have been enough to dethrone Big Red.
From the forbes.com
Would he declare an end to his reign, or would some seismic shift dethrone him?
From the usatoday.com
They still don't have enough to dethrone the champs, but they'll be fun to watch.
From the ocregister.com
He put his seven sons in key positions and had a plan to dethrone the Achamenids.
From the en.wikipedia.org
Will a new contender emerge this season to dethrone defending champ Virginia Tech?
From the sportsillustrated.cnn.com
If he finishes in the top seven, Power would have to win the race to dethrone him.
From the kentucky.com
Quimby and the Laramie officials meet and use a technicality to dethrone Lisa.
From the en.wikipedia.org
Quimby and the Laramie officials look for a way to dethrone and silence Lisa.
From the en.wikipedia.org
More examples
Remove a monarch from the throne; "If the King does not abdicate, he will have to be dethroned"
(dethronement) deposition: the act of deposing someone; removing a powerful person from a position or office
(Dethroned) Ring of Honor (ROH) is an American professional-wrestling promotion, founded in 2002 by Rob Feinstein, and owned by Cary Silkin. ROH currently runs several wrestling shows each month throughout the midwest and on the east coast of North America. ...
To depose; to forcibly relieve a monarch of the monarchy; To remove any governing authority from power