There are a few ways to do this.
I’ll preface it by saying that BY FAR the best way to do things is to regularly check for updates and install them yourself when you know it’s safe, so that programs are not forcibly closed, etc. However, I understand the frustration you feel, so…
The best way is to set your internet adapter to be a metered connection. Microsoft won’t download any updates except the most critical fixes over this type of connection. Click start, go to “Settings” and then select Network and Internet. Depending on if you are using Ethernet (network cable plug) or WiFi, choose one from the left side.
If you choose “Ethernet” you will see your ethernet adapters. Click one, select properties, and then switch it to a metered connection. IF you choose “Wi-Fi” you will then need to choose “Manage Known Networks” and choose the one you use, select properties, and set it to a metered connection. If you connect to another WiFi, it won’t think it is metered by default and may download the updates, just FYI.
Alternately, you can get some sort of hardware or software firewall (even Windows Firewall will work, I suspect) and block all traffic from *.microsoft.com and *.windowsupdate.com. Now, this is a BAD IDEA. The reason is because IF windows update manages to start before your firewall does, then you could have to deal with a “Stalled update” and those can be a tremendous pain in the ass. Any other hacks to stop it are even worse than this, so don’t use them.
Your only other option would be to get a subscription to Windows 10 Enterprise edition, which has some functionality that will allow you to prevent updates. It’s $84 a year, I think.