Go to YouTube like videos playlist. Execute this script in console. Will start to remove likes from videos

remove-liked-videos.js

const sleep = time => new Promise(resolve => setTimeout(resolve, time))
let items = []
const interval = setInterval(async function() {
    if (items.length < 10) {
        items = Array.from(document.querySelectorAll('#contents ytd-playlist-video-renderer:not([is-dismissed])'))
    }
    if (items.length === 0) {
        clearInterval(interval)
        return
    }
    const item = items.shift()
    item.querySelector('yt-icon-button').click()
    await sleep(50)
    const drops = document.querySelectorAll('ytd-popup-container iron-dropdown ytd-menu-service-item-renderer paper-item');
    (drops[3] || drops[0]).click();
    await sleep(50)
}, 200)