How Remove photos from one device only

How do I remove photos from one device only whilst keeping them safe in iCloud and other personal devices?

Here's what happened: I signed into my personal Apple ID to download some personal apps on to my work (employers) iPad. Which we are allowed to do. However all of my personal photos (thousands) now populated my work iPad which I do not want. after signing out of my personal Apple ID and re-signing in to my work Apple ID they still remain even though I turned of syncing with icloud. Please help me remove them without losing them across all devices. There must be a simple way......