Beginning with the Windows 10 Anniversary Update, updates from Windows Update, Microsoft Store, and other Microsoft content come through Delivery Optimization. This reduces the time and bandwidth needed to get updates.
Note: Turning off Delivery Optimization doesn't disable updating, it simply forces each device to download its updates directly from Microsoft, rather than getting them from a local machine that previously downloaded them.
If the toggle to turn Delivery Optimization off is unavailable, like it is in the image below, that's because your device is managed by your organization and your IT administrator requires Delivery Optimization to be on.
Select Start > Settings > Update & security > Advanced options > Delivery Optimization.
Turn off the toggle under Allow downloads from other PCs.