how do i delete all my emails at the same time?

You can only delete 50 emails at a time in both full featured and Basic Mail. Put a check in the box at the top left of the list to select and then hit Delete.

https://help.yahoo.com/kb/SLN16015.html

To mass delete the spam folder right click on the folder name and Empty Spam.

To mass delete the trash folder right click on the folder name and Empty Trash.

Yahoo Contact Number @ 1^800^218^8813

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