If you choose not to download and install an update, it’s available for you the next time you visit Windows Update…and the next time, and the time after that as well. You might have a good reason for not accepting a particular update—perhaps it makes improvements to a Windows feature you never use—and there’s no reason it should clutter your list of available updates. To remove an item from the list without installing it, you hide it. This is a pretty easy trick, but the option for hiding updates in the list is itself somewhat hidden and often goes overlooked.
In the list of available updates, right-click any update that you don’t want to see again, and choose Hide Update. If you later change your mind—or if you just want to see a list of the updates you’ve chosen to hide—on the main Windows Update page, click Restore Hidden Updates.