My daughter’s phone and my phone share photos and I want her to not get my photos. She has been using my Apple ID. I just got her her own Apple ID. However her phone still has my Apple ID and we cannot delete it. What do I do?

Have you followed the following steps? They are from Apple's support document Sign out of iCloud on your iPhone, iPad, iPod touch, Apple TV, or Mac

Sign out on your iPhone, iPad, or iPod touch

1. Go to Settings > [your name]. 
2. Scroll down to the bottom.
3. Tap Sign Out.
4. Enter your Apple ID password and tap Turn Off. Forgot your Apple ID password? 
5. Turn on the data that you want to keep a copy of on your device.
6. Tap Sign Out.
7. Tap Sign Out again to confirm that you want to sign out of iCloud.

Note point 5 which offers to keep certain content on the phone after it has signed out of the iCloud account.