The unused administrator account will not be deleted

Hello, I’d like to inquire.
I’m going to delete an administrator account that I don’t use on the administrator page. But even if I click the button to delete the user from the list, it won’t be deleted.
Is there something wrong with the setting?

You have to have at least one admin user, so the last admin user cannot be deleted.

There are many accounts with administrative authority…
I want to erase all three of them, but they can’t be deleted.

Sorry, I cannot read the error message.

I’m sorry! It’s Korean.
That message is 'Should I delete the user (support@1-2-3-4-5.Studio)?
Even if ‘Delete’ is selected, it will not be deleted.

I couldn’t find a way… so I deleted it from FTP’s “Account”!