Did Rimuru Kill Clayman?

Rimuru kills Demon Lord Clayman and is officially recognized by the other Demon Lords.

Can Rimuru defeat milim?

Rimuru won over the mighty Milim Nava to his side, and he fought the holy knight Hinata Sakaguchi to a standstill in an intense duel.

Who controlled Clayman?

Kazream himself personally designed Clayman to be a tactical commander and a schemer, similar to himself and created him for the expressed purpose of turning him into a Demon Lord. 300 years ago, He became one of the Ten Great Demon Lords with Kagali's help.