How to unload a QPixmap

[MorrisLiang]

In one of my class,there's a member QPixmap object:

MyClass
{
   ...
   private:
      QPixmap myPixmap;
}

MyClass
{
   ...
   private:
      QPixmap myPixmap;
}

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I will load a picture into it.And after a period,I want to unload the data (nullify it),make it just like uninitiated.How can I do this?