He was a good guy, and a great employee. But then I caught him in bed with my pikachu, so I had to have him offed.

To "off" a person means to kill them. It is a slang term and implies that they were killed in a routinized gangster (not gangsta) fashion, rather than in self-defense or in a fit of passion. It is insultingly casual, and should never be used in a formal situation, or when you want to convey the least scrap of sensitivity.

Off is also the name of a popular brand of insect repellent, more properly rendered "Off!".