A HEPA cleaner can be cleaned, but care should be taken not to damage it. It is best to clean the filter in an area with proper air flow to prevent the dust particles from affecting anybody.
The best way to clean a HEPA filter is to start off using a compressed air canister. The HEPA filter should be placed over a trash bin, and the compressed air should be used to get all the dust off the filter; this should be done on both sides and repeated. After using the compressed air, the HEPA filter should be washed off outside with a hose. Make sure to control the water stream when using the hose, because the pressure can damage the filter if it is too high.