This is for the ridiculous inventions studio. The reason Scratch Cat is undeletable is because if you look very closely at his paw you can see a USB stick. That USB stick programs him or any sprite holding it to be undeletable. As it says in the project, just drag Scratch Cat into the bin, make sure he is touching it! Also, when you click the red button, the Scratch Cat that isn't angry that is on the poster might be there, that is not a glitch but when you drag it that it goes to the front layer.