Assuming you are talking about a water filter:
Most carbon filters will have their own housing that can be removed for easy cleaning. To clean the housing, simply remove it and rinse it with warm water. Be sure to let it air dry completely before putting it back on the filter. If your model does not have a removable housing, you can still clean it by rinsing the entire unit with warm water. Again, be sure to let it air dry completely before using it again.