New iPhone iCloud question

So I have the new iPhone, and for about 3 years now I have been paying for the iCloud storage 2tb

all my pictures& video is automatically backup to iCloud; but since having my daughter I’ve been so afraid to delete pictures on my actual phone. I’ve now come to the conclusion that having 45,000 pics is just to much... so I guess my question is, is it safe to delete all the pictures on my iPhone device after it’s uploaded to the iCloud