Ough Every time i enter a palace he starts talking, in front of the guards, about me killing the Emperor for the glory of dark brotherhood. Its not a surprise that Luchien Lachance ended up dead in oblivion since he cant keep his mouth shut. Is there a way to dismiss him?

And a second question. What is the maximum number of followers you can have? Currently i have the spectral Assasin, Lydia, a Dewmer war machine and my horse Shadowmere

Just kill him or conjure something.

Cicero: "stab stab stab stab stab stab stab aaand stab stab stab stab stab stab stab!"

Listener: "Shut up Cicero. nobody asked you but you are correct."

Cicero: "Yes.... listener."

Kill him.

Summon something else.

He's not particularly durable, which is a shame, since you can only summon him once a day. That said, it shouldn't take much to kill him so you can move on.