Could you share a screenshot showing the error you are seeing and a little additional context into the back of what you’re attempting to do.
I know there’s been issues with some of Roon’s cloud services since the DDOS attacks on Thursday so it’s possible their accounts management services are still affected.
Roon are investigating and making infrastructure and security changes to mitigate against such attacks.
We’ll need to know the current status of this issue (including a screenshot or some of the information @vadim has requested above) in order to take any effective action from here.
One option, if you have a reliable and verified Roon Backup handy, is to completely wipe the Roon Server folder housing the database from a file explorer. You’ll need to have network access to the server machine from another desktop.