I don’t have the storage for my Dark Elixir from the clan pass. How do I burn Dark Elixir when I have Town Hall 7?
I am a TH9 CoC player, and I got confused also the first time when I saw the overflowing Season Bank Loot. But the thing is that the EXTRA loot still stays. Like your Storage of Gold is 4,000,000 and you have 3,000,000. Your season bank is 5,000,000. So you then have 8,000,000 gold even if your storage is only half the cash. But when it becomes 7,999,999 gold, it's not becoming 8,000,000 again.
It will fill the empty storage, and any remaining that you earn will fill it again as space frees up. After that, you can't collect more Dark Elixir from the Drills.
If you aren't sure about how to spend the dark elixir, just rush your TH to Level 9 where you need a lot of dark elixirs to upgrade your heroes alone.