Unused assets being included in build

I’m making a web player game and want to keep the size as small as possible. For some reason, some assets that I remove from the game are still being exported during the build, and the only way I’ve found to make it stop is to remove those assets from the project folder. They are not located in the Resources folder or any other special folder.

I’ve right clicked on the assets and checked the “Find References in Scene” option, but it also finds nothing.

Is this a bug? If not, is there another clever way to locate exactly where assets might be being referenced?

when you make your build, make sure you only include the scenes you need to.
when unity makes a build it includes everything you have in the project folder regardless whether you are using it or not. If you say that removing the assets from you project keeps the build file smaller, then Unity probably includes everything from the project to the build.

So it is best to only have what you need in the build in your project.

you can have several projects like that to only concentrate on current work, if the project is huge, and then combine it all to last.

you can make you own unity packages from you projects and then include them all in one bigger project to make the build.