2 Chronicles 22:7-9

New King James Version

⁷ His going to Joram ^(A)was God’s occasion for Ahaziah’s ^[a]downfall; for when he arrived, ^(B)he went out with ^[b]Jehoram against Jehu the son of Nimshi, ^(C)whom the Lord had anointed to ^[c]cut off the house of Ahab. ⁸ And it happened, when Jehu was ^(D)executing judgment on the house of Ahab, and ^(E)found the princes of Judah and the sons of Ahaziah’s brothers who served Ahaziah, that he killed them. ^9 (F)Then he searched for Ahaziah; and they caught him (he was hiding in Samaria), and brought him to Jehu. When they had killed him, they buried him, “because,” they said, “he is the son of ^(G)Jehoshaphat, who ^(H)sought the Lord with all his heart.”

So the house of Ahaziah had no one to assume power over the kingdom.