kan je zorin 17 ook opschonen zodat alle overbodige troep- er uit is
Go to software store there you can remove many packages.
You can use the sudo apt autoremove Command to remove no longer needed Packages. But becareful with this and check what will be deleted before You delete it.
Alternatively, there would be the Ubuntu Cleaner or Bleachbit (Is similar to CClenaer from Windows if You should know that).