I have some previous answers that will hopefully be helpful:

During the Christian occupation of Egypt, what did they think of the pyramids?

How did early Muslims view the ancient Egyptian pyramids?

Why did the Sultan of Egypt Al-Aziz Uthman attempt to demolish the Pyramids in the late 12th century?

Briefly, yes sometimes the smaller structures were torn down and reused for other purposes, such as when Cairo was built, or to expand Cairo's defensive walls. For the bigger monuments like the pyramids, apparently at one point sultan al-Aziz tried to knock one of them down, but it turned out to be so huge that it wasn't worth the effort. Otherwise they didn't really understand them as ancient religious monuments that needed to be destroyed. The pyramids, especially, were associated with events in the Bible/Qur'an or other Christian and Islamic stories.