Google Chrome "Managed by your organization" when you don't have an organization?

Starting with Chrome 73 when one or more policies are set in the Chrome Browser you'll see "Managed by your organization" at the bottom of the 3-dots menu and at the top of your Chrome Settings screen.   I'm posting this because, first of all I posted it as an answer on Googles support forums and it's pretty clear from the many confused, freaked out, wrong answer posts after that nobody there actually read it; and  Google's official answer isn't terribly useful.  For starters they don't tell you how to clear it.  The links in their answer also aren't helpful if you're a HOME USER who isn't using a Chromebook or your company's G Suite or an organization's computer.  I'm going to tell you below how to get rid of this notice and take control of your browser.

This notice is normal if you're in an enterprise setting like a business or a school where the IT Department is managing the browser capabilities or if you use G Suite for business and you're logged into an account associated with G Suite.

However it's disturbing to suddenly see it when you're using your private computer at home with your personal account!  If you're using Chrome on your personal computer and saw this "Managed by your organization" appear don't worry, it *probably* doesn't mean anyone hijacked control of your browser.

I say "probably" because there are malware and malicious extensions out there that can reset your home page and/or search engine and they do this by creating Chrome Policies, which will trigger the "Managed by your organization" notice. Allowing an extension to run in or even trying to print from "Incognito Mode" can potentially trigger this, but will persist even when you're back in a normal browsing window.

Deleting accounts or profiles or creating new ones won't get rid of it.   Uninstalling and reinstalling Chrome doesn't work.  It might initially seem like it got rid of it, only to have it show up again.  You may have read somewhere that chrome://flags/#show-managed-ui  will fix it.  That just HIDES the notice, it doesn't change any of the managed policies.

Policies apply to ALL users and are set in the operating system not the browser. Unless you're using a Chromebook, then it's managed in the Google Admin Console and applied through your Chrome Profile.  This image explains how it works (image is a link to the Google page about it):

First see what policies are being set and by what by typing in:

chrome://policy

At the top are the "Chrome Policies" set administratively. If under "Applies to" it says "Machine" and the "Source" says "Platform" those are policies that were set ON your computer, they are NOT being managed remotely by Google or nefarious parties unknown.

If there are any extensions setting policies you can simply remove the extensions. Though some extensions NEED to set policies in order to work, for example password managers. That's why it's important to learn what policies they're setting and why.

MAC

On Mac this is pretty easy. You don't even need an Administrative level account.

1. Write down each "Policy name" (they're case-sensitive)
2. Quit out of Chrome entirely
3. Got to Applications → Utilities → Terminal
4. In the terminal type the following for each Policy Name (example is "HomepageLocation"):

defaults delete com.google.Chrome HomepageLocation
Hit enter. Do this for each Policy Name until they've all been deleted.

5. Restart Chrome. If you did it right the "Managed by your organization" at the bottom of the 3-dots menu should be gone. You can double-check by going back to chrome://policy which should be empty of policies now.

Note that if you miss or leave even ONE you will continue to see the "Managed by" notice.

WINDOWS

Windows has tools you can download a fixer app:

Chrome Policy Remover: https://drive.google.com/uc?export=download&id=0B5uG-tHNHBj5XzNJbzlsd0NONnc

You can also do the fix manually by deleting a registry entry:

\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome
or
\HKEY_CURRENT_USER\SOFTWARE\Policies\Google\Chrome

Then run the Chrome Cleanup Tool:
1. Open Chrome
2. Go to the 3-dot menu and "Settings"
3. Click "Advanced" at the bottom of the Settings page.
4. Under "Reset and clean up" click "Clean up computer"
5. Click "Find"
6. If you're asked to remove unwanted software click "Remove"

Linux

It uses a JSON file to set user, rather than group, policies for the browser.  It's rather complicated.  Here's the Chromium Project page explaining it: http://dev.chromium.org/developers/how-tos/enterprise/adding-new-policies

Ultimately if you know they're being set at the operating system level (and if you're not on a Chromebook they will be) and you have administrative privileges on the computer (which you probably do if you own it) then YOU are the "organization" that is managing these policies.