One of the smartest moves I made this year was to drop the unlimited on 2 of our phones. 10gb shared data. Eliminated the overage that the phone with 2gb had. Picked up tethering and dropped ipad plan. $100 a month savings.
That's smart because you didn't have unlimited. You had unlimited and 2gb throttled.
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As others have said- did it through apple App Store. Showed before and after hitting confirm unlimited data.
What is your new plan then?