Cleaning a fan grille? Unplug first and check the model's instructions
Never reach into a running or plugged-in fan. Disconnect power, remove accessible dust with a soft cloth or vacuum and open a grille only when your model's manual permits it.
Vornado demonstrates cleaning a model 660 by removing its front grille, but even 660 units can have different screw layouts depending on production date. Do not apply its removal procedure to other fans without checking their manuals.