Unwatched all the repos you were automatically subscribed to when you joined an organization.

githubUnwatcher.js

// Works on https://github.com/watching
// Just edit the variable below, got to the page above, and paste this code in the console.
// Will need to refresh and repeat if more than 100 repos
let unsubFrom = "buzzfeed"; // Case sensitive

document.querySelectorAll('.Box-row').forEach(entry => {
    if (entry.innerText.includes(unsubFrom)){
        entry.querySelector('button').click()
    }
})

No worries!
I think I've stumbled upon a Medium article on Google when I was searching for how I can easily unwatch an organisation's repositories.