i thought you need to be Guild master and the guild need to exist more then 24h?
else try this:
1. 1 lv 20+ twink in guild.
2. Make a Guild Assist. to twink.
3. Now Click on Quit Guild but D0n't press OK with Lv20 twink.
4. Now Since the twink is already Assistance, Send Guild Leadership from Main character to Twink.
5. Now you were on Hold For Step 3. and you are also getting Guild Leadership, so you are quitting and getting leadership then press OK. OK. and now Your Twink is Leader and leaving the guild at same time.
6. Withdraw with Main Character coz you cannot kick him at the moment.
7. Approve the withdraw from Lv20 Twink.
You Main Character is out from guild right there and after 24hours twink will be out from guild as well.
Like this you don't have to delete twink and leader is out of guild on time as well