|What you are referring to as the E: drive is a vitual CDROM drive and you can use it to mount ISO images & volumes so that you can access their content without burning to disk.|
If you are able to run MagicISO then select view from the menu options and select settings, then click on the tab titled Virtual CD/VDV drive. From there you should be able to enable or disable the virtual drive as you wish.
If however, you want to total uninstall magicISO then you should be able to uninstall it from
control panel > add remove programs and select magicISO from the program list.
☺ When everything else fails, read the instructions.