How to delete an image from axMapControl component?

Question

I have a problem in arcgis c#. I am using Arcgis axMapControl component and adding image to it but I can not delete image when wanted to delete from axMapControl component... I have get a exception such as " The process cannot access the file C:\Users.. because it is being used by another process "

Thanks for your help.

public void Add_map()

  IRasterLayer my_raster = new RasterLayer();
  my_raster.FromFile(path);
  AxMapControl1.AddLayer(my_raster);
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public void Delete_map()

AxMapControl1.DeleteLayer(0);
System.IO.File.delete(path);    //There is a Exception.... This problem...