In a nutshell, the Rebbe advocated against going to college for 2 primary reasons. 1) the kefirah that lies within much of the teaching, 2) the environment of "pritzus" (for lack of a better term). The Rebbe further said one should not think they can withstand those issues, as we ask everyday, al t'vienu lidei nisayon. The Rebbe himself brought up that a person could taaneh, "but the Rebbe went to college", but that too is not a reason to put yourself in such a nisayon.
So those who follow "in the footsteps of the Rebbe" will listen to what the Rebbe said and not go to college.
There were individuals who the Rebbe did tell to go to college, and many (if not all) who had already started college were instructed to continue, even if they wished to drop out and go to yeshiva.