Is it possible to disable the Files tab from the Chat Window in Teams

PEGGYATA I hear you, anyone with a background in Knowledge Management and Information Architecture would see the issues with allowing unmanaged content to accumulate. However we lost already, users want immediate self-service teams, just to drop a file in chat, random sharing from OneDrives etc. In the past I surveyed users, they are clearly more satisfied with an open, uncontrolled service. My role was always to improve user satisfaction, to allow them to be happy like a pig in document mud.

Only in very specific industries documents have sufficient value that organisation beats immediacy, so unless you are engineering a plane, nuclear reactor, law firm etc. then it's simply not worth resisting unstructured collaboration.