Simpler and more direct way, without requiring learning that YET;
Logged in as admin, go to Appearance, then Widgets, then ADD the Widgets that you do want. Until you add some explicitly, WordPress shows Search, Pages, Links, Meta, etc. by default and you cannot remove them.
Once you add one or more, though, the other ones that were shown by default are no longer displayed. You’re back in control and you don’t have to edit your theme to accomplish that, just a few mouse clicks.