How can i delete all of my emails from inbox at once? (I have lots of emails in my inbox )?

I prefer to do this page by page. I start with the oldest. There is usually at least ONE message I want to save. Using the boxes on lefthand side, I CLICK on the topmost left box, (actually left ABOVE the first message). You can also use the 'SELECT ALL' box at bottom left. BOTH will check all 25 messages on that page. I can then UNselect any odd messages that I am not ready to delete just yet. Then Use the 'delete' key.Smetimes Yahoo will ask you to confirm this command.

Select all or theres a option called sender ,select it and delete.

Move all your inbox mail to junk mail folder. then click on the word empty beside the junk mail box on the left hand side of screen, and now all is empty, make sure you dont have junk mail you want before doing this.

If you have Yahoo mail, you can't. All you can do to speed up the process is to click on the little box on the top left of your messages to select all of the ones on your screen and then hit the delete key. At least you can delete one page at a time that way.

Click on the first email, hold down the shift key and click on the last email and then click on delete - that will delete them all in one go.

You click "select all" at the top-left and then delete. If you have more than one page, just do that again. Hope that helps.