One review that I removed in particular troubles me to this day, and that's the lukewarm, C+ review I wrote of Bong Joon-Ho's "Mother," which I saw, for the record, at its New York (and maybe U.S.) Premiere at the 2009 New York Film Festival. I deleted the review because I changed my stance on the lead performance not off the film, but off of my memory of the film after time had passed. I found this to be bad because I was perhaps shifting to a perspective that was not my own and I was second-guessing myself. I look back on my cutting of that review wistfully. I should have thought more about it, as it was a good review, IMO, and I wish I could have that one back.
The other was my review of "Slumdog Millionaire," which I originally called the best film of 2008 (A), a statement I retracted and then went against with a somewhat biased re-review (C). I took it off eventually because it seemed to me as somewhat unfair to rewatch one movie and to not re-watch others. To my credit, there was merit in re-watching it, as I was somewhat troubled by if the film would suffer on a second viewing.
There have been other retractions too, (such as "Happy-Go-Lucky (A)," "Police, Adjective (B)," and "Doubt (A)"), but I can't remember all of them right now. Feel free to ask my opinion on a certain movie, because I may have seen it and then retracted the review.