Deleting unused assets

I want to get rid of assets in a scene that are taking up a lot of space and I am not using. I have a very small scene in which I imported various textures to try as fills. The scene file size is very large, 450 mb for 5 secs. and when I look in the package contents of the scene, every texture I ever tried is there. Even those where I deleted the texture in the colour palette. About 300 mb. of this scene consists of textures that I am not using. How can I get rid of these? I tried trashing them directly from the scene. The scene opens and runs, but it crashes when saving, even when saving as a new scene.

Thanks.

Please contact support@toonboom.com as we would need to see the scene to resolve the issue.