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 if it is unique (base/Personal Archive/ssh identity.
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.