Done and Archive are incompatible. Delete.. Delete..

If you ever want to delete a G-email from its notification itself in your Android phone (may be in iPhone, too), set 'Delete' as a default action instead of 'Archive' in Gmail app and 'Bin', instead of 'Done' in Inbox app.

Gmail notification

Email deleted

Inbox notification

At present, no undo for Inbox app

Steps!!?

Find it yourself. It's there in settings.

Well, if you are a dummy...