After extended use, a computer's tower fan can experience dust and dirt build-up inside. Because of this, it should be opened up and cleaned every six months (sooner if you have allergies or see dust building up along the plastic venting).
Unplug the fan from the outlet. Locate and unscrew all the outer screws holding the assembly together.
Use the flathead screwdriver to pop up the top control panel. The control panel is the top piece of the tower fan that has all the electrical wiring and settings buttons on it. It's on the top 2 inches of the tower fan and has a visible separation split in the plastic. Pry the screwdriver around the edges of the split to unlatch the plastic snaps holding it in place.
Pull the control panel up slowly. Unlatch the electrical cord snap. The electrical cord snap is where all the wiring comes together. It has one main plastic snap piece that connects the top control panel section to the bottom part of the tower and then runs to the bottom of the unit and out to the outlet.
Use the flathead screwdriver to unlatch the remaining snaps holding the two main plastic covers together (down both edges of the tower fan).
Pull the central blade assembly up and out. This piece is connected with a series of small plastic blades, all stacked up. With this pulled out, you can wipe off each blade section as well as the inside compartment. All the main parts are now taken apart and can be cleaned as needed.
An air compressor is a useful tool for blowing out dust and particles.
Do not pull too hard on the snap, or it could break.