How to (mass) delete comments from comment activity history.

After searching via Google i have not come up with and answer that actually works . This is two parts:
First part is access on a PC: I would like to know how to find my comment history and delete comments from that area, and specifically if there is a method for marking and deleting multiple comments at once.

Part 2 on Android app: I can find the comment history on the android app but can only delete one comment at a time by navigating to the comment and then deleting it. I would like to know if there is a way to mark a comment (or multiple comments) and delete them directly from the comment history.