You can't stop them - Windows 10 consists of a continuous series of updates - but you can exercise a great deal of control over them.
The first thing to do is to setup Active Hours. That's a contiguous block up time, up to 18 hours, when Windows 10 will not restart to finish installing an update. Find the settings at Start menu > Settings app > Updates and Security > Windows Update.
If it's outside Active Hours and Windows detects that you're still using your computer, e.g., you're typing on the keyboard or moving your mouse, you'll be prompted with a very noticeable message box in the lower right corner of your screen that lets you choose when Windows will restart.
If you have the Professional edition of Windows 10, you can use the Group Policy editor to delay receiving updates in the first place, but only Active Hours controls the restart.