Disabling akondi: press 'alt+f2' on the keyboard to bring up the Run dialog box, start typing 'akonadi' and 'Akonadi configuration' will appear in the drop down menu. Click it and go to the Akonadi server configuration tab, then press Stop at the bottom right plus un-check 'Use internal MYsQL server'. A notification should show that akonadi has been stopped.
1. Disable Semantic Desktop
a: System Settings -> Desktop Search -> Basic Settings, un-check 'Nepomuk' and 'Strigi' if it's not already.
b: System Settings -> Desktop Search -> Desktop Query, un-check “Index files on removable media” and un-check every folder under “Customise index folders…”
c: System Settings -> Desktop Search -> Backup, set “Backup frequency” to Disable
2. Disable Nepomuk related notifications:
a: System Settings -> Application and System Notifications -> Manage Notifications, un-check all the “Show me a message in a popup” under “Desktop Search” and Semantic Desktop”