That's true, but only, if he/she is an admin or if he/she is able to convince the admin/admins of those other websites where are the no-follow links to do so.
So, what I think is that you are right in case it's your own website and you are the admin (or you know well the admin, you're a friend of the admin, the admin is working for you and you're the website owner, etc.), but in the rest of the cases (situations) it's what johnniewalk already said : You may only contact the website owner from which site/sites you got backlink/backlinks in question and ask him/her to remove it/them.
That's the way it is.