Through the editor yes, make the chairman really old is one way I've done it, you could try making your club one of the chairman's disliked clubs or put the club into administration, then he will leave.
if you look into the chairmans current stats theres a rating in there somewhere (maybe contract section) called board confidence reduce it(as far as you like)i used the value 10 to get rid of gillett & hicks from liverpool usually by the end of september.. even got some billionaire italian take over once promising 350m for new players if the take over went through.. i was dreaming of messi & co with a liverbird on their chest.. it went through!!! an i ended up with 17m and chris brunt!!! dont think i've ever been as disappointed with the game an i've been playin sinde 95/96..