Moderators are appointed for life as discussed in this post. Not having a term limit seems reasonable, but is there no way for a moderator to be recalled by the community? No reelection and no recall authority seems rather like a dictatorship.
If you think a moderator is out of line use the "contact us" link at the bottom of the page to explain your position to the team. Moderators have been removed in the past.
Other moderators can ask to have a colleague removed. This is the officially sanctioned process for "normal" removal of a moderator.
Beta site get pro tem moderators appointed by the team rather than elected and they have to run for election to retain their position after the site launches. And permanent moderators have been known to resign.
At this time that is it.