No — removing, deactivating, or setting a user to "former" doesn't affect the companies themselves or anyone else's access.

• Nothing happens to the companies. They aren't lost, deleted, or unassigned as a result of removing a user.
• If you review a company's access afterwards, the former user simply no longer appears in the list of users with access to it.
• Other users who have access to that company are completely unaffected.

There's no cleanup or reassignment step needed — removing a user just revokes that person's own access, and everything else stays exactly as it was.