You can remove it from add / remove programs, just click on the add/remove windows componants, scroll down until you see internet explorer, untick it, click apply, or next and follow it through.

Now,

Getting IE 6 back on there could be a bit tricky, Microsoft seem to only list IE7

You could repeat the above steps and see if it installs IE 6, or try this link and see if it's any help ?

http://www.microsoft.com/windows/ie/ie6/default.mspx

HTH