This isn't any better than jhocking's answer, but is a different way...
Double-offset the image, and then crop it.
- Duplicate your layer (drag it onto the New Layer icon at the bottom of the Layers palette)
- Offset the top layer to the left
- Filter > Other > Offset
- Set Horizontal to the negative sum of the pixels you are removing and where you want them to be removed from (-104 in your example)
- Make sure
Undefined areas
are set to transparent
- Offset the top layer back to the right
- Filter > Other > Offset
- Set Horizontal positive offset where you wanted the removal to start (+4 in your example)
- Make sure
Undefined areas
are set to transparent
- Reduce the canvas size
- Image > Canvas Size
- Reduce the width by the number of pixels you removed (reduce by 100 in your example)
- Make sure you choose an anchor point from the far-left column.
- Flatten the layers (Ctrl + E)
You can turn this into an Action if you need to do it to a bunch of images...