sounds like you need to create a support ticket
https://support.frontier.co.uk/kb/
as only they can sort out account issues
from your post I understand you have made a mistake, the rest makes very little sense to me, I would inc on the ticket a very detailed description of your problem if I where you in order that they fully understand what you have done and what you want to do I mean you say things like where all games are activated is that a steam thing if so frontier is not steam so its them you need to contact regarding steam issues not frontier
as for linked accounts I don't think they can be unlinked once linked so good luck with that as I really have no idea
this forum however is a different entity apart from may share access password from the game and in order to delete forum accounts I think you may need to private message a community manager of the forums and ask him to delete your forum accounts as I am pretty sure you cant just diy
as to why you need to delete forum account too is beyond me?, why not just abandon ,dont use it any more?...... still you must have your reasons and I believe contacting a forum moderator via private message to the community manager (Tim Smith) is the only way I am just not sure is all
