If you ever want to remove the webhook from your discord server, first right click on the channel in your discord server that you set up the alert in. Then, choose Edit Channel.
Next, go to integrations, and then click on Webhooks.
Next, you'll see the list of webhooks set up in that channel. You'll need to click on the arrow next to Raider.IO to expand it. At the bottom of the window, you'll see the option to delete the webhook.