Locate the plastic knob labeled "Ionizer" on the top of the air purifier. Push the knob over to the position labeled "Off." Disconnect the air purifier's electrical cable from the wall outlet.
Hold the left and right sides of the plastic grill unit on the front of the Holmes air purifier. Pull the grill slowly forward to unhook it from the main body of the air purifier unit.
Grip both sides of the foam "pre-filter" component inside the air purifier and slide it toward you. Set the foam pre-filter aside.
Locate the plastic HEPA (high efficiency particulate air) filter, which is positioned inside the air purifier behind the foam pre-filter. Grab the left and right sides of the HEPA filter and pull it directly toward you to remove the filter from the purifier's main body and complete the disassembling process.