Sign in to your Yahoo Mail account
Open the folder you want to clear, such as Inbox or All Mail
Click the checkbox at the top to select all visible emails
If prompted, choose the option to select all conversations in the folder
Click Delete
Repeat the process for other folders if needed
Empty the Trash folder to permanently remove the emails
On mobile, open the Yahoo Mail app
Go to the folder you want to clear
Tap Select
Select all emails or individual emails
Tap Delete
Empty the Trash folder in the app if needed