Open Gmail
Go to the left sidebar
Find the label or folder you want to delete
Hover over the label name
Click the three-dot menu next to the label
Select Remove label
Confirm if prompted
If it is a system folder like Inbox, Sent, Drafts, or Trash, it cannot be deleted
If you want to remove all emails from a folder, open the folder
Select all emails
Click Delete
Empty Trash if needed