These cartomizers are a disposable item and are not really cleanable. There is some basic cleaning you can do, but as for the heating element and filler there is no cleaning process. Once these become clogged, they need to be recycled or put in the trash.
Every time you refill a cartomizer or every few refills it is best to clean the threads of the cartomizer with a paper towel. This will help keep everything clean and the right amount of power making it to the coil. E-liquid will sometimes make its way down to the threaded connection and it does need to be cleaned up.
Top Cap Cleaning:
It is best, when you refill your cartomizer to wipe down and clean out the grooves in the bottom of the white rubber top cap. This will help prevent eliquid and condensation from building up and coming out the top.
**** DO NOT*****
D not try to clean the cartomizer by soaking them or rinsing them. If you try to clean the inside of the cartomizer the cotton filler will take too long to dry out and can grow mold or bacteria. If you try to fill it while wet, the water soaked cotton filler will not wick well and the water will prevent the cartomizer from producing vapor.