A really bad mass YouTube channel unsubscriber!

mass-youtube-unsubscriber.js

var i = 0;
var intval = setInterval(unsubscribeFromChannel, 1000);

function unsubscribeFromChannel() {
	let gridContainer = document.getElementById("grid-container");
	let channelShelf = gridContainer.getElementsByClassName("ytd-expanded-shelf-contents-renderer");

	if (i < channelShelf.length) {
		channelShelf[i].querySelector("[aria-label^='Current setting is ']").click();
        
        
    	// Click unsubscribe entry in listbox
    	let paperListbox = document.getElementsByTagName("tp-yt-paper-listbox")[0];
    	paperListbox.children[3].click();
    	// Click unsubscribe button in confirmation popup
    	let confirmPopup = document.getElementsByTagName("yt-confirm-dialog-renderer")[0];
    	confirmPopup.querySelector("[aria-label='Unsubscribe']").click();
	}
    i++;
    
    console.log("Unsubscribed from " + i + "channels.\n");
    console.log(channelShelf.length + " channels remaining.");
}

Go to https://youtube.com/feed/channels/ and paste script into browser console.