Howdy,
After reading your post again, I am uncertain whether you meant to describe a situation where you found the magazines in the doorway or merely left by themselves somewhere in the enclosed entryway. If they were the only magazines present, then I would have less of an objection to your removing them - but there would still be an argument why you should not have taken them even in that situation.
If however, what occurred (or if the situation was this way in another setting) was that the mags were there, along with other magazines, for people to browse or read while they are waiting or even to take and read (like a newstand with free circulars or Penny Savers) then I disagree with the comments that have stated that it is ok and reiterate that I don't believe it is appropriate to just take them and dispose of them.
In situations were someone has left publications/penny savers/free newspapers/advertising etc. it is not appropriate for a person to simply take them and dispose of them, unless they are the "owner" or are in charge of controlling that space.
Simply because they are free for you to take does not justify taking them and disposing of them because there is an implied purpose that one who takes the free item will at least use it or in this case read the material. (Incidently what is left is really immaterial. It could be literature to browse ro take or it could be free jelly beans.)
In taking the magazine with no intention of reading it yourself you deprive someone who might enjoy reading the material, usurp the right of the person who controls the space (who incidently might approve of the leaving of the WT magazines), and of course set aside the good intention of the Witness who left them. (This is like grabbing a hand ful of the jelly beans with intention beforehand to just throw them away.)
If the situation is that there is a bunch of literature there for persons to browse or take to read then again the appropriate response is that you should either leave your own literature to counter the speech that you find offensive or in lieu of that (and if you feel strongly about it) speak to the person in charge of controlling the space and inquire about whether they are aware that the WT literature has been left, (perhaps mention why you feel that their patrons would not benefit from such material) and ask if it ok if you remove them and dispose of them. (Someone mentioned the hypo of Nambla or pro-terrorist literature - and again I believe that the appropriate response is to inform the person in charge of controlling the space.)
Of course, if you accept a piece of literature or take something that is free, with the intention of seeing what it is (or sampling it), you are not under any obligation to retain it and may throw it away immediately if you so desire.
But in this case you knew what it was before hand, and decided before hand to remove the material so as to prevent anyone else from reading it, and in so doing you substituted your own feelings and judgment for someone else's and that was wrong of you to do.
(In a way it is no better than what the Society/JWs do themselves when they discourage the reading of anti-JW information by the faithful and wrong for the same reason.)
The act doesn't make you an "apostate" by the way - just a really bad person. (just kidding!) If it makes you feel any better you are welcome to by one of my "Apostate and Proud" t-shirts http://www.cafepress.com/oroborus21jwnet/1373652
-Eduardo