John Gill Commentary 2 Kings 10:17

"And when he came to Samaria, he smote all that remained unto Ahab in Samaria, till he had destroyed him, according to the word of Jehovah, which he spake to Elijah." — 2 Kings 10:17 (ASV)

And when he came to Samaria, he slew all that remained unto
Ahab in Samaria
All that were in any connection with him, as related to his family, or as ministers of his in civil or religious things:

till he had destroyed him ;
his whole house, as he was ordered:

according to the word of the Lord, which he spoke to Elijah ;
which is observed, to show the exact fulfilment of prophecy, see (1 Kings 21:21) .