How can I delete all emails in an iCloud mail account

Decmom Said:

"How can I delete all emails in an iCloud mail account all at once?"

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Create a Single Mailbox:

Perform this on Mail on a Mac: You could create a single mailbox, and then drag-&-drop all other mailboxes and mail to it. From there, right click on it, and select to delete it. Use a computer to perform it this way.