While you’re here, if you are upgrading a Fusion drive and abandoning the internal HDD, pop the SATA cable to disable the drive without needing to disassemble the whole mini. See the HDD replacement guide steps 14-16. Reinstall the shield while leaving the cable disconnected.
Upgrading my Fusion drive to an OWC 1TB SSD was a piece of cake with this guide. I didn’t bother removing the old spinning drive; I just popped the SATA connector and left it unhooked.