title: Removing iOS SDKs from OSX
body: <p>This isn't a programming question but it's about the SDKs and the IDE.  I've accumulated a ton of different XCode installs over the past couple of years and now my hard drive is nearly full.  With each SDK clocking in at around 5 gigs, and my storage space getting low, I have a couple of questions</p>
  
  <p>3 Questions:</p>
  
  <ol>
  <li>Can I remove old ones?  </li>
  <li>Where are they stored?</li>
  <li>Does the newest SDK overwrite base classes from previous SDKs? (Does NSString.h now reside in two different SDKs or will the newest one take precedence?</li>
  <li>What about beta 1, beta 2, beta 3 SDK versions?  Does installing the GM/official eliminate the beta version from my Mac?</li>
  <li>Most importantly, Can I still target 3.0 if I install the 4.2 SDK? (I understand the difference between base SDK and target SDK)</li>
  </ol>
  
  <p>I want to clean my hard drive and I have about 18 GB remaining on a 160 GB drive.  I'd like to just start over and reinstall OSX, download a fresh SDK, but I still have apps that are targeted to 3.1.2 and I don't want to be forced to only support 4.0.</p>
  
  <p>Thank you</p>