Open Gmail
Select the checkbox at the top to select all visible emails
Click the trash icon to delete the selected emails
If prompted, choose to select all conversations in the inbox
Repeat on other tabs or labels if needed
Go to Trash
Click Empty Trash now to permanently delete the emails
Use search filters like older_than:1y or has:attachment to target specific emails
Archive emails instead of deleting them if you want to remove them from the inbox without deleting them
Unsubscribe from unwanted mailing lists to prevent new emails from arriving
Create filters to automatically delete or archive future emails
Check Spam and Promotions folders if you want to clear them too