Youtube delete all liked videos. Hover your mouse on the 3 dots then hit F4. If video is deleted, go with the mouse to the next one. Install AutoHotKey first.

yt-remove-liked-videos-v2.js

//Open DevTools and paste this in Console.
function sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
}

async function deleteLikedVideos() {
    'use strict';
    var items = document.querySelectorAll('ytd-menu-renderer > yt-icon-button.dropdown-trigger > button[aria-label]');
    var out;

    for (var i = 0; i < items.length; i++) {
        items[i].click();
        out = setTimeout(function () {
            if (document.querySelector('paper-listbox.style-scope.ytd-menu-popup-renderer').lastElementChild) {
                document.querySelector('paper-listbox.style-scope.ytd-menu-popup-renderer').lastElementChild.click();
            }
        }, 100);
        await sleep(500); // sleep cause browser can not handle the process
        clearTimeout(out);
    }
}

deleteLikedVideos();

yt-remove-liked-videos.ahk

#MaxThreadsPerHotkey 2

F4::
Toggle := !Toggle

loop
{
    If not Toggle
        break
    Send {Click}
    Sleep 200
    Send {Tab}
    Send {Up}
    Send {Enter}
    Sleep 200
}
return

For [Deleted Video] or [Private Video] You need to open YT App and delete them from there.

There is a bug in YT Web for that kind of entry.