Aperture Library and Photo

I have Photo installed on my Mac (running OS X Yosemite 10.10.3) and I have around 76GB of photos on Photo and something like 82GB on Aperture. I get a message from Aperture that the content has been moved to Photo. Can i safely delete Aperture and its library? Do I currently have two sets of photos on my hard drive? Why, if it says it has moved the content, does Finder still show that there is over 80GB on Aperture?