Delete Multiple Collections at Once

Is there a way to delete multiple Collection or selected Collections all at once?
I’m reusing an old project file for another project and want to strip out all irrelevant Collections.

I don’t think there’s a way to select multiple Collections at a time, but it’s pretty quick to select a Collection and click the - button in the upper right corner.

If you have your own base setup you like to use for your projects, once you get this one cleaned up, you might like to go to File → Save as Template. This way, you won’t have to go through and delete Collections, etc. for your next project.