I am also waiting for a solution to this. I have an older PC that I use to train and experiment with, and have had to reinstall Windows several times. Each new installation is registered as a new machine in Link to Windows on my Cat S42. So it's not a Samsung problem.
Microsoft support asked me to sign out of the account on my phone. It didn't work.
I have deleted user data and cache on the phone, uninstalled and reinstalled several times, and all the PCs that no longer exist are still in the overview on the phone.
I've been wondering where this information is stored. It must be on one of Microsoft's servers, and I think the problem is possibly related to the fact that each Windows installation gets a unique ID number. Renaming the computer after Phone Link is connected to the mobile is fine.
The app works just fine, and I hope Microsoft finds a solution to this soon.