Can't figure out how to remove *multiple* images in my Library at once?

Tech savvy gal here, but I am at a loss and I suppose this is not a feature (yet?) Seems simple but it appears I can’t do this function: select multiple photos from my image library to delete at once. Currently, I have 500+ images in my library, (as a floral designer over the years, it adds up and I am trying to clean this out because it runs super slow with that many in there and yes, we have HIGH speed internet, brand new macbook- but the library takes a very long time to load and it’s because I have way too many photos in there). But I can only delete one at a time *ugh*, and that is not going to happen LOL! Am I missing something here? Thank you!