So I use OSX Server at home, it’s handy. If you ever get stuck on the number of resource in use by the calendar (I use it to store copies of my bills/on the date I charge them). You should look at https://github.com/trevor/calendarserver/blob/c9970b06a70445ca75b62e3d170c26bc897a035e/calendarserver/tools/test/deprovision/caldavd.plist
The settings described in the plist are the most helpful. along with serveradmin stop calendar and serveradmin start calendar they enable the most configuration. You should also look at – https://manuals.info.apple.com/MANUALS/1000/MA1183/en_US/iCalServer_v10.6.pdf though you should note that many of these things changed in the latest version of OSX Server.