User blog comment:DaNASCAT/Technical Update: January 20, 2016/@comment-24055022-20160120205858/@comment-5558012-20160120210755

Every user can't delete their comments on the forums; what is currently possible is removing them (even doing so other users can still see them if they know what they are doing).

Deleting comments can throw off a conversation and really isn't something every user should be able to do, at least in my opinion.