Cannot get rid of current postgres installation

Ths installer created the .plist entry in /Library/LaunchDaemons/postgresql-15 and uninstaller left that intact. Because of this I cannot reinstall new version of postgres application as I alway get the message that an instance of this app is alredy running - no wonder, since the launchd daemon starts this at each reboot.

How can I delete / remove that "postgresql-15.plist" file?