This is a script that adds a delete button to clean up a playlist (Watch Later/Liked videos ...etc) so you can delete videos quickly without opening a menu.
Copy the following code and paste it in the devtools console after you open the playlist page:
const videos = document.querySelectorAll("ytd-playlist-video-renderer");
for (const video of videos) {
const deleteButton = document.createElement("button")
deleteButton.innerHTML = `x`;