A collective noun refers to a group of people or things.
So, "guides" refers to a group of people who guide others. Here are some examples:
* A group of guides took the tourists on a tour of the ancient ruins.
* The guides were very knowledgeable about the local history.
* The team of guides ensured everyone had a safe and enjoyable experience.
You don't need to use a different word to make it a collective noun; it's already one.