Cookies are entirely dependent on the browser cache of the end-user / recipient of the email, there isn't really anything you can do if a lead has already been cookied.
Regarding URL tracking, if you normally build landing page or email URLs with "utm" tracking parameters, just delete those from your links and resave. Doing this still won't affect any information carried around by a lead via cookie, however.
Out of curiosity, what is the use case here - why do you want to remove all tracking info?