I asked the Intersystem-Support:

Hello Mr. Graupner,

Thank you for contacting us in Support regarding this question. Unfortunately there is no 'ccontrol rename' on Windows. This command exists on Unix and VMS to change instance name. There is an enhancement request already in the works (ProdLog 57340), and I have noted on the report that it would have utility on your site as well. The proper way to rename a Cache instance on Windows is to re-install Cache. If you desire the same directory structure, you will need to save off a copy of your configuration, uninstall, then install fresh with the correct name and move in the saved-off configuration. Let me know if you need any assistance with these steps.