Spitballing here but since AK is a global thing - In the EU you have a 'right to be forgotten'. If one wishes to exit a forum and have most traces of what you've published there deleted, it is yours for the asking. Unless someone quotes you everything you've posted goes down the hole. Might entail sending a registered letter to AK's headquarters.
Like I said, spitballing. Take it for what it's worth.
The US is in the process of considering legislation to do the same. In the meantime, AK, being global in reach, has had to comply with that regulation, for more than one EU-based member who requested it.