Deleting photos out of "Photos" Application

I am trying to give my friend my Macbook Pro. I deleted all icloud / google accounts, but the my photos that were once synced from the the icloud are still in the "Photos" application. How to I get those pictures to not show up? If I delete them from the "Photos" application on the Macbook since its no longer connected to the icloud, will they delete from my icloud too? I've tried with a couple pictures and it doesn't seem to delete them off my phone but I want to make sure before I hit delete on 9000+ pictures.

Thanks!