Is there an easy way to cut a slice from an image using Gimp?

Here is a method that is quick and often does what you want:

1. Cut out the middle, leaving a transparent "hole".
2. Click anywhere to remove the selection (so the hole is not selected).
3. Click Image > Zealous crop .

This is going to remove the middle part. However, if you also have transparency in other parts of the image (like around the edges) it's going to remove that transparency too.

I believe you're asking to do something like cut out the middle of a page, leaving the header and footer and have the blank space removed with the cut action, effectively joining the header and footer together.

To my knowledge, I don't believe so. Even if you cut, or delete, that space is still part of the image even without content.

But, you would be able to highlight the top or bottom (or left or right) of the remaining space and drag it to align with the other side. It's not ideal for repetitive tasks, but should get you through if you only have to do it a few times.