Unfortunately that's outside of the power of the city to do. There is, however, a ranked ballot initiative, which might otherwise be titled the, "Never elect Rob Ford again" initiative, because his hope to win is to run up the middle between two or more "best" alternatives, which wouldn't work if people picked a second or third choice.
All that being said, it's very easy to think of Rob Ford as the worst mayor ever, but during his tenure as mayor how many mayors of Montreal have been arrested for corruption? Mayors take huge bribes from organized crime to illegally award construction contracts that cost cities millions or tens of millions. Rob Ford's criminal contacts are not large or organized enough to help him fudge numbers nearly that large.
I'm not convinced that Toronto is a worse place for having elected him over his closest contender in the last election (George Smitherman, nicknamed "Furious George" for his temper tantrums and bullying while a provincial minister). Rob Ford had one year to mess things up and then he was sidelined by council. I kind of like council running things and ignoring the mayor. It's, you know, democracy. My worry is that Ford will be re-elected and council will make the mistake of thinking that he now has a "mandate" and they have to listen to him. If he god re-elected and council went right back to the business of ignoring him, it would probably be fine.