In 1946 Königsberg was renamed into Kaliningrad. Kaliningrad got its name by Mikhail Kalinin, a Bolshevik revolutionary. All other cities, after 1991 and fall of Soviet Union, that got there names by communist or socialist was changed except this one. Is there any reason for this? If there is, what is the reason?
No, many cities and places that have names after Bolshevik leaders kept them. I mean, right on the front page of the subreddit right now, there's a question about Leningradskaya Oblast retaining its name.
Anyway, not to discourage anyone else from further answers, but /u/Lithium2011 gave a decent answer last time this specific question came up a month ago.