The View > Clean Up By feature in Finder is one of the best and fastest ways to clean up any folder that has fallen into disorganized chaos. It’s mainly used for the Desktop, but can be used elsewhere as well.
But if you go to the View menu, you might find that the Clean Up By and Clean Up Selection options are grayed out. What gives?
The explanation is simple: these options are only available when you’re in Icon view. So if you’re using any other view type — including List, Columns, and Cover Flow — then you’ll have to switch back to Icon view by clicking on the four-in-a-square button:
But if the Clean Up options are still grayed out, you need to do one more thing: go to View > Arrange By > None.
This is because Arrange By automatically keeps your folder organized according to the arrangement method. Clean Up is there for when you aren’t using any of these auto-arrangement methods.