Icloud

Basically, I lent my sister one of my old iPhone when her phone broke and she ended up keeping it for 2 years so I now have thousands of her pictures in my Icloud. She recently signed out but all her pictures are still in my Icloud. Is there a way I can delete the photos and videos from just that phone off my icloud as theres about 17,000 so I'd rather not have to do it one by one.

Thank you

Annie