There have been many complaints, comments, feature requests, and posts regarding the difficulty surrounding deleting emails in Inbox by Gmail. More specifically, bulk deleting, or deleting with fewer clicks, has been a huge request of users since Inbox rolled out.
I am not one that uses deleting much, if at all, especially since switching to Inbox. However, that does not preclude me from showing you a quick, low click method, to delete many emails quickly.
Next, you want to use the Shift # shortcut to start deleting. This will start from the top email and keep pressing Shift # to delete. The process will start with the first email that was in focus. To make sure it is in focus, open the email and then close it. If you want to skip and email, go to the next one, open it, close it, click Shift # and the process will continue from that email.
Thanks to a co-Gmail Product Forum Top Contributor (Wendy), it was brought to my attention that this can be accomplished in one keystroke of # instead of Shift+#. To do this:
"To move the focus (the blue bar) into the Inbox message list when you start Inbox , or into a bundle you‘ve just opened, press the right arrow key, and then control its movement with the left and right arrow keys or the “j” and “k” keys.
Once you move the focus to a message, then any of the keyboard shortcuts can be used to perform actions on the message, e.g. delete (#), reply (r) or forward (f), pin (Shift-p) or mark as Done (e). And as in Gmail, “o” or “Enter” opens a message, “Esc” or “u” closes it again, and pressing “c” will open a Compose box to write a new message." Reference: http://gmail-miscellany.blogspot.co.uk/#navigation
There you go, a quick low click method to delete your emails in Inbox by Gmail. Below is a video of it in action, see no clicks.
Note: This tip is for Web Only, not mobile.