My mistake - I didn't read the comments...
It really leaves trash after unistall.
And to delete this trash, you'll need to visit Mysql.
And after this, WP didn't let me in to admin area - it removed my administrator role. There was no trick to change it (not in Mysql directly). In the end I was forced to reinstall WP and to create all my content again.
Sorry guys, nothing personal - it just didn't suit my needs.