Apple Device Syncing

Having issues syncing my iMac to my iPhone. My iMac is synced to my Macbook and I removed the sync chain from the Macbook side but it still shows on my iMac which will not sync to my iPhone at all. I do not care to have the Macbook synced to anything but do want the iPhone and iMac connected.

How do I remove my Macbook from my iMac?

When I scan the iMac QR into my iPhone, nothing happens…