Can yo cut the top off of a pine tree without killing it?

Depending on the individual tree and the amount removed, yes. This frequently happens as a result of mechanical damage (wind/snow, etc) or an insect or other creature feeding on it. Afterwards, the tree may stop growing upward (especially in older trees or with severe damage), or one or more branches under the area may take over as the tip of the tree and grow upward. The area is vulnerable to rot and other diseases, though, so death is possible.