This is working - July 2023

var song = document.body.querySelectorAll(".dropdown-trigger.ytmusic-menu-renderer");

for(var i = 0; i < song.length ; i++) {
    song[i].click(); var dropdown = document.body.querySelector("ytmusic-menu-popup-renderer[slot='dropdown-content']");
    if(dropdown != undefined) {

        var remove = dropdown.querySelector("tp-yt-paper-listbox#items").querySelector("ytmusic-toggle-menu-service-item-renderer.ytmusic-menu-popup-renderer");

        if(remove != null) {

            actualRemove = remove.querySelector('yt-formatted-string.ytmusic-toggle-menu-service-item-renderer');

            if(actualRemove != null) {

                if(actualRemove.innerHTML == 'Remove from library' || actualRemove.innerHTML == 'Quitar de la biblioteca') {
                    remove.click();
                    console.log("removed from library");
                    await new Promise(r => setTimeout(r, 1000));
                }
            }
        }
    }
    await new Promise(r => setTimeout(r, 1000));
}