How do I turn off Shared Library Photos on my iPhone?

My boss set me up to have access to his entire icloud. So we both activated Shared Library and he entered my email address/Apple account to have access to his entire icloud. He has a total of nearly 38k photos and videos in his icloud. Now that Shared Library is turned on, I can view ALL his photos and videos in my iphone’s Photos (even without internet); I don’t want that. I only want to access his icloud on a browser whenever I need. Basically, I do not want his photos and videos to show on my phone. Please help. Thank you!

[Re-Titled by Moderator]