Unlinking
I have 2 iPads and one can see what the other is doing. How do I unlink these so they are separate?
iPad Air 2 Wi-Fi
This sounds like a situation of multiple individuals sharing the same AppleID ???
If so, the best, most secure, and BY FAR cleanest way-ahead for the long term is to have separate AppleIDs for each individual.
Create a new AppleID for the “other” iPad’s “primary user.”
https://support.apple.com/en-us/HT204316
If the new AppleID is for a child, there is a slightly “different” method involved.
https://support.apple.com/en-us/HT201084
If desired, you can then “selectively” share services using Family Sharing.