Changed Server IP - Infrastructure still reporting

Hi,
I had an infrastructure app setup at a server: server1.blahblah.com. We then decommissioned the box and pointed the IP at a new server (new-server.blahblah.com).

NR Infrastructure is still reporting data for serer1.blahblah.com even though that server doesn’t exist anymore. Where in the configuration files can I tell Infrastructure that this server doesn’t exist?

Thx