Can you kill Yes Man? THank you in advance.

Save your game, choose a weapon, and find out. :gun:

I have, but everytime I enter Vegas he's still there. Does he REMAIN dead? I don't think so.

I remember him saying something like " If i die i'll just respawn as another securitron" or something along those lines.

During the dialogue with him you can say you'll kill him, he'll then explain how a part of him is in every securiton and he'll just take over another if his current form dies. Think Mr. Smith in the Matrix