Mass Delete Discord Messages in Bulk

Note: You can only delete your own messages, even on a server where you can’t delete messages.

Step 1:  Download a browser extension for running user scripts.

Step 2: Install the Undiscord script.

Get the script from: OpenUserJS or Greasy Fork.

Step 3: Open Discord in your browser.

Go to https://discord.com/login and login to your Discord account and go to the server and text channel where you want to delete messages.

Step 4: Click the new trash icon in the top right in Discord.

Click on the Authorization, Author and Channel buttons.

Step 5: Click on start.

And let it do its job. This can take a really long time depending on how many messages you have sent in that channel.

DO NOT SHARE YOUR DISCORD AUTH TOKEN
Sharing your authToken on the internet will give full access to your account! There are bots gathering credentials all over the internet.