It can get worse. I promise I am not as evil as this will sound. Post a bunch of inappropriate stuff to global and clan chat until someone reports you. If you make it bad enough, you may bet a permanent ban. Mix in all genres of inappropriate including violence, terrorism, explicit stuff, curse words, racism, and offers to buy and sell accounts/gems. Then make his base into something inappropriate.

Spend all his loot and gems. If he's an elder or coleader kick everyone out of his clan. If possible, dissolve the clan so they lose all their xp. They might reform later, but you can bet they'll never let him in again.

Check and see if he is close to achieving any achievements. If so, complete them for him, then burn the gems. Also, drop all his trophies.

Use the contact us button in help to rant against Supercell with some more really inappropriate stuff. That way they know who to ban right away.

Finally, if you have his password, you should be able to delete his village entirely and permanently. Borrow a device from a friend who does not play clash or use gamecenter. Download clash and create a gamecenter account. Link the new clash village to the new gamecenter account. Then sign in on his device or on your device with his gamecenter. Click the option to load a different village and in his gamecenter make the new clash village the one associated with his game center account. Then log in to gamecenter on his device and make the same change. If the village isn't on his device and it's not on his gamecenter, it only exists on the SC servers. And after what you just told them, good luck getting them to help you recover it.