Way to de-rank without throwing?

[Kaawumba-1133]

Decayed account are matched at their pre-decay MMR.

@Kaawumba-1133

To prevent rank camping, for players ranked 3000 SR or higher, their rank will decay 25 SR per day if they do not play. Each game a player plays increases his buffer by 36 hours, to a maximum of one week (20). Each day a player’s decay buffer decreases by 24 hours. If it hits zero, decay starts. To determine how many games must be played per week to avoid decay, we can calculate (1 game / 36 hours) * (168 hours / week) = 4.67 games / week. This is slightly lower than the 5 games per week that was originally reported (15). To see if decay is imminent look on the right hand side of the information screen of the competitive play card. After returning from decay, the player will have a substantial SR buff (gain more SR from wins than he loses from loses) until he is back where he was (3). While decayed, a player’s MMR (and hence matchmaking) does not change (3). The decay clock doesn’t start until the player does his placement matches.

(3) Overwatch Forums
(15) https://www.youtube.com/watch?v=Jqf0e8zzyCw#t=5m7s
(20) Overwatch Forums

And no. There is no way to lower your MMR intentionally without engaging in unbecoming activity.