The lead designer of the meta game systems (such as Ranked, Clash, and Matchmaking) at Riot Games released a post detailing the discontinuation of position ranks and a reset of the ranked ladder with demotions to all players in Diamond and above.
League of Legends Ranked Reset: Everything You Need to Know
SapMagic states that feedback has been positive or promising thus far on the splits system and the reworked placement matches, and of the various new systems introduced, these had been the most successful.
For position ranks, SapMagic cites the player dissatisfaction, and that it could not be addressed in the near future with tweaks to the existing system. Thus, the position rank system will not see a global rollout later in the year, and its current preview in the North America and South Korea regions will end on March 13. Players' highest rank will become their new rank post-rollback of the system. Any rewards and Promotion Helper benefits will be retained.
For players in Diamond and above, the addition of new tiers in Iron and Grandmaster caused bugs which allowed players to reach Grandmaster with a sub-40% win rate, as well as allowing some Diamond players to reach higher ranks than intended.
Consequently, all players in Masters and above will have their rank reset to Masters 0 LP. Players in Diamond will be demoted by one division, floored at Diamond IV. Any rewards earned will be retained, but will be adjusted to reflect the player's new rank. Grandmaster and Challenge will temporarily be locked after the reset, set at an as-of-yet undefined time in late March. These changes will affect all regions.
Images courtesy of Riot Games