Psalm 18's title says David sang it when the LORD delivered him from all his enemies and from whom?

Answer: Saul

Its title calls David "the servant of the LORD," who sang this song when delivered "from the hand of all his enemies and from the hand of Saul."

“For the choirmaster. Of David the servant of the LORD, who sang this song to the LORD on the day the LORD had delivered him from the hand of all his enemies and from the hand of Saul. He said: I love You, O LORD, my strength.”— Psalm 18:1 (BSB)