I am rejoining Destiny after a 4 year leave of absence, and am locked in my founded clan as the last member. I've tried through the in-game client, companion app, and bungie.net to disband the clan to no avail - I will note that bungie.net reports that I "have insufficient permission to perform this action."
Per my screenshot, the destiny 2 app reports 6 current members, in spite of me being the only member in-game, on the app, and on bungie.net. I've tried every avenue and method to disband this clan, and at this point I might just need divine intervention from staff. Thank you in advance!
This is caused by some clanmates not migrating their progress from Battle.net to Steam in the allotted time.
Luckily, there is a fix, but it may not seem ideal:
You'll have to make a dummy platform account, log into with Bungie.net with it, and get that account into your clan. Then you'll be able to make it the Founder, this is where you can leave the clan on your actual account.