<p>I was tethering with my phone for internet access and noticed it was eating my data like crazy. I found that auto-updates were updating my packages and system in the background</p>
<p>This can be turned off via GUI or Terminal</p>

Method 1 - GUI

Open "Software & Updates"

Go to the Updates Tab

Change "Automatically Check for Updates" to: Never

Change "When there are security updates" & "When there are other updates" to: Display Immediately

Method 2 - Terminal
<p>Edit /etc/apt/apt.conf.d/10periodic:
Change All of the values to 0 (add comments of original values for switching back if desired)</p>
<p>And you have successfully turned off automatic updates</p>
<p>Remember to turn it back on if you want it when you are hooked up to wifi or ethernet</p>