The file type I have is in stl.I have tried so many times but in vain. Please help ..
Select the desired entity or "Hole" in product tree right click on it an then select Delete option.
You can hide it by right clicking the entity or "hole" and then Hide option.
If its .STL file you'll need to feel them out one by one with surfaces. On generative shape design or Wireframe And SUrface Design select the "Fill" option and start selecting the closed contours.
Hope this helps.