That error is unrelated to deleation. You are using new character table with old, custom, or modified l2server.jar.
Indeed the error is unrelated to deletion, but quite contrary to the previous post, the error is due to using a
new, updated, or modified/custom l2jserver.jar with an old character table.
Basically, the java side has a query that contains a field which is missing from your database.
That being said, I do not recommend deletion a clan via the database. First of all, the server caches all clan info at boot time (almost

most is actually loaded when the first player logs in). So if you delete a clan from the database while the server is running, you'll run into various issues.
If you delete the clan while the server is offline, you need to also make sure to delete all info related to the clan:
change the clan_id and priviledges of all members of that clan to 0.
wipe all clan castle, clan hall, and clan war issues.
wipe any (possible) clan quests that are still ongoing...
I'm a joyful, merriful, playful, curious, young, little elf!!!

I'm also a High(tech) Elf, (computer) wiz!