System updates are good and one should not avoid them. Company policy do address that.
There are couple of computers that shall disobey such rule for a damn good reason.
Is there a way how to prevent automatic scheduled updates and reboots and prevent remote administration to reenforce this regime back?
FIrst off, Run5k's comment is correct. If these are corporate systems, and you are not the responsible IT administrator for them, you need to talk to the responsible IT administrator for these systems about this. Assuming you convince that person that you really do need these system to not reboot on their own, feel free to point them at this answer for an explanation of one way to do that.
Second, there are very few cases that you're likely to convince any seasoned IT professional that these systems need to both not reboot on their own when an update hits, and not handle updates as part of regular maintenance during scheduled downtime. There are only two cases I can think of that need such a setup, long-running operations being left to run overnight, and people who insist on leaving everything open as a reminder of what they were doing instead of using more reasonable methods. The first one is trivially solved by just pausing updates when you start the operation, and I have zero respect for the second one as it's not a reliable method to achieve their desired effect even without automatic reboots for updates.
Now, with all of that out of the way, you can get some configurations similar to the old Windows 7 update options through the use of group policy. The relevant entry is in the Windows Update subsection of the Windows Components section of the Administrative Templates, and is called 'Configure Automatic Updates'. Settings of 2 and 3 can be used to require manual installation, which means in turn that the system won't reboot by itself.
