How to remove default xmlns entries when serializing a class

I created an instance of a class that is serializable and I serialize it to a file, but it always puts the following attributes in my root element:

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" 

      

        
        
        
      

    

How can I stop this?