I'm trying to clear some space in my macbook pro and when I go to pictures I see applications "iPhoto library" and "Photos Library". They are each about 25 GB but I never use them and don't plan to do that. Can I delete the pictures in them?

I'm trying to clear some space in my macbook pro and when I go to pictures I see the applications

"iPhoto library" and "Photos Library".

They are each about 25 GB but I never use them and don't plan on doing that. I do have load of pictures in my computer but they are all stored in my dropbox and I never willingly upload them to either of those applications. Are the photos in those apps stored twice in my computer? Can I just delete the photos in the apps with out deleting the ones that are in my dropbox?

I'm super confused about all this and any help would be really appreciated!