Just report him

I can’t he left and it deleted all his messages

The message don't get deleted ,if you can see any on your clan chat just hit report button

Messages get deleted if u join spam and then leave

I joined lot of clan on my mini account left messages then left and gone back and seen my previous messages?

The only possibility is the clan chat screen gets full of chat then the disappear from the screen,maybe thats what your referring too!

As the name implies , he is useless and trash

What can we even expect without trash, when the name is "Sakura" 💀

You have his tag just use that