We enabled Communities in our production environment, and now, non-admin users are reporting they see this new black header at the top of Salesforce. I believe this bar is called the "Global Header":
While trying to figure out how to get rid of this thing, I found articles on the web (salesforce.com) on how to enable this header using permission sets, but have not found a way to disable it.
Strange that it turns on for non-admin (plus admin) users by default. I would think that would something one would want to explicitly enable.
Per request of glls, we are not yet using any templates. We simply enabled the Lightning Communities feature.
Best Answer
You are correct - this bar is called the "Global Header", which is visible only in Salesforce orgs using Salesforce Classic. It can be disabled by turning off the "View Global Header" option in the "System Permissions" section of all your active permission sets.
According to some really old release notes, you can't disable this permission for standard profiles, which conflicts with current documentation that says "the View Global Header permission is disabled by default for all standard profiles." So, depending on when your org was created, you may or may not be able to disable it for standard profiles.