Summary: How to delete old versions of Rhino.
Related installation help: Troubleshooting Rhino 5 Installation

Can I delete older versions in Add or Remove Programs without causing problems?

The Add or Remove Programs entry in the Control Panel in Windows reports all Service Releases as an installed program, each using approximately 250MB of disk space. This is somewhat misleading. Windows reports the total as if all the installed files are added on to the existing installation even though many, if not all, files are actually overwritten on installation. Do not use the Add or Remove Programs to remove older Service Releases of Rhino 5.