You want to punch a hole?
Simply create a compound path.
For other forms of combination use the pathfinder panel.
You’ll nee to be a bit more precise. What sort of shape are you dealing with?
Pathfinder (panel) will probably be your friend,
Sorry, very new with AI. I have a version of a logo on a brochure. It is a long streach of buidings in the background that wraps around from the front of the broshure to the back.. It had two maginifying glass over the buildings, a lager one on the front page and and a smaller one on the backpage. I am takeing this image to use for another project and need to altar it. I had to remove the smaller magnifying glass over the buildings (the buidings are one object with different roof lines). Now where I removed the magnifying glass there is as section of the buildings I want to remove and then bring the two end sections of the buildings back together. Maybe this isn't the place to ask for this but I need step by step help if that is possible. Or, if you know of a link to a video tutorial....
You might want to read the section about the pathfinder panel in the manual: http://help.adobe.com/en_US/illustrator/cs/using/WS714a382cdf7d304e7e07d0100196cbc5f-6462a .html
Is the row of buildings a pixel image?
If so, you might be better off doing the job in Photoshop.