External

Internal

Thunderbird Cleanup on Mac
iCloud Contacts Cleanup
iCloud Calendars Cleanup
iCloud Drive Cleanup
Remove internet accounts. Go go System Preferences → Internet Accounts and remove all external internet accounts.
Remove private keys from ~/.ssh and store it on Rackstation in base/Personal Archive/ssh identity if it is unique.
Log out from and remove Spotify.
Deregister the Mac from Kindle
Log out from iMessage and remove the message database from /Users/<username>/Library/Messages
Remove "Downloads" files.
Safari: Remove passwords: Preferences → Passwords → Remove all. Remove cached website data: Preferences → Websites → Remove all. Safari → Clear history → All history.
Chrome: log out from the google account and Turn off sync and personalization. Clear browsing data.
Save ~/VMware Fusion VMs. There is a script on RackStation (/volume1/base/Software Archive/pull-windows-vmvare-vm) that pulls the VM from the Mac and stores it on Rackstation. For the script to work, you need to enable ssh access to the Mac and update the IP address.