MyCloud 5 app deleting photos

So, I have a little problem with my MyCloud 5 app because it is taking up 100gb+ on my iPhone. I was wondering if I can just delete the photos I don’t want there or not because when looking up the location it shows me the location from the cloud drive. So I’m worried that if I delete them on my phone that they will also be deleted on my drive.
I appreciate the help.