The avar remains (although I think they can’t change/delete it until they rank-up again), and so do the Merits. What shifted downwards was likely the post count, leading to the Activity, leading to a demotion in rank.
Thanks for confirmation it seems angone wanted to demote their ranks can simply delete their post right? But I doubt there are legendary or hero ranks that would be willing to demote their ranks just to start to a lower rank again. Thanks tis is helpful.