A vertical tower fan may include a control unit, a fan unit having a shaft, a shell assembly and a main body. A securing unit supporting by a number of resilient units is disposed underneath the control unit. When the user wants to remove the fan unit from the fan, he/she can simply lift the securing unit, and the top portion of the shaft can be separated from the securing unit. Meanwhile, the bottom portion of the shaft can be removed from a protrusion, so the entire fan unit can be separated from the fan for cleaning or repairing without using any tools.