delete pixel from the raster image with specific range value

[chrischris201444 at gmail.com]

any idea how to delete pixel from the raster image with 
specific range value using numpy/scipy or gdal?

for example i have a raster image with the
5 class :

1. 0-100
2. 100-200
3. 200-300
4. 300-500
5. 500-1000

and i want to delete class 1 range value
or maybe class 1,2,4,5