Abolition of the Caliphate
The Ottoman Caliphate, the Muslim world's last widely recognized caliphate, was abolished on 3 March 1924 (R.C. 1340, A.H. 1342) by decree of the Grand National Assembly of Turkey. The process was one of Atatürk's reforms following the replacement of the Ottoman Empire with the Republic of Turkey.
Source: Wikipedia — Abolition of the Caliphate (CC BY-SA 4.0)