Delete devices and zones

I used my roon core (mac Mini with Linux and core build 511) 2 times at the location of a friend of mine. He is using an Auralic Aries, wants to by a nucleus and wants to have a look at roon before. The second time the roon core knows everything I configuered the first time. That’s ok. But now I want to delete the zone and device that I configured for him. Is there a way for that? I can not find anything if I use my core at my home.

Second question: his lan is not connected to the internet until now. Every time I searched for an artist or others it lasts very long. Much longer than at my home where I am connected to the web. Is it possible that the core also has a look at the web in case of searching?

Kr Günter

is there no way to clean up the database?
i have now a new streaming bridge and want to delete the data of the old one.
any suggestions?