By an interim, non-elected government, after months of escalating riots.
True. People should read Richard Sakwa on this matter. According to his well-researched 2015 book, Frontline Ukraine, armed insurgents marched around the debating chamber, instructed MPs to not follow the formal investigatory procedure needed for impeachment, and just to "sack" Yanukovych.
I mean, Yanukovich had also left Ukraine at that point anyway.