Unfortunately according to the documentation, the standard Gmail service doesn't have the ability to permanently delete messages, only to move them to the trash. However, there is the option to use the Advanced Gmail Service instead which provides the full power of the Gmail API, and does have a delete method. Couple of things to note:

Delete email permanently in Gmail | Blog | Limilabs Delete email permanently in Gmail If you delete a message from your Inbox or one of your custom folders, it will still appear in [Gmail]/All Mail . Here’s why: in most folders, deleting a message simply removes that folder’s label from the message , including the … How to Delete a Gmail Account | PCMag How to Delete a Gmail Account. Whether you're ghosting on someone or just want to get rid of long-dormant old email accounts, here's how to permanently delete your Gmail address. How To Delete Your Gmail Address Permanently [July 2020]

How to Delete Gmail Account Permanently | All Tech Share

When I use Shift+Delete on Outlook 2013 to delete emails permanently from my Gmail account's inbox, the emails don't get deleted from Gmail; instead, they become archived in Gmail. If I try to delete the emails by just pressing the "Delete" key, the emails go to Gmail's Trash folder in Outlook.

Jul 24, 2020

So you finally decided to delete your Gmail account. maybe you don’t want to use Gmail service anymore or any other reason. let’s move forward there is no big task to delete Gmail account. it’s a very simple procedure you just need to follow my steps to perfectly delete your Gmail account permanently. Before You Delete. How to Delete a Google Gmail Account - Lifewire Mar 31, 2020 Delete your Google Account - Google Account Help