How to delete the link between files and talk app

I am having issues with files that are being linked to talk conversations.

For example, I shared a file with user1.
I then started a conversation with user1 and the file is showing under related resources.

The topic of the conversation is ‘project1’. I would only like files pertaining to project1 to show in this conversation.

How do I select which files to show as a related resource to this conversation?