How to: Use Hazel to clean your desktop
1 Create a new rule
Install Hazel, and open its pane in System Preferences. Click the + button in the Folders column. Select Desktop from under iCloud in the sidebar, and then Open. Click the + button under Rules to open the rules sheet for Desktop.
2 Define your rule
Name your rule ‘Desktop clean-up’, and set the conditions for the rule to run. Have the first condition be ‘Date Added is not in the last 30 days’, and the second ‘Size is greater than’ along with a per-file size in MB you don’t want to exceed.
3 Set a target folder
For the ‘Do…’ line, leave the Move action as-is, and set a non-iCloud folder to move matched documents to, such as ‘Documents – local’ (if you already have that – otherwise create it first in Finder). Click OK and your rule will start running.