Some settings are managed by your organisation

This is probably a stopgap solution put in place to stop windows updates being automatically pushed, as sometimes windows updates can cause assorted issues with GPD devices.
Note that it doesn't automatically mean that the system is being controlled by another party - it's just the default message that appears when some kind of restriction is placed on Windows by the admin.

You can toggle the setting in Group Policy. See here for a quick guide: https://www.askvg.com/fix-some-sett...re managed,in RUN dialog box or search box. 2.

If you've not encountered any issues so far, I'd suggest leaving it alone personally.

Another possibility is that you've installed Office via signing in with your workplace email address. Last time I did this, there was an option you could select that would not give up control of your device's settings, might be worth a double check Graham.

Also, if Windows Defender is turned off, I would recommend having a look at recent reviews for other free antivirus/antimalware software.