In 99.9% of cases we will tell you why we deleted your account.
However, if you're a bot, troll, spammer, or something else along that par, we do not need to give you a reason as to why you've been banned or restricted from using the forum.
Its there as a right, for the administration to delete/remove/revoke your account access to the website with our without warning with reason or without any reason at all. Very simple, and its found in the majority of all Terms of Services agreements.