The following guide will allow you to uninstall a kext using Single User Mode during boot when a kext that you have recently installed is causing your system to not boot. The installation VodooHDA.kext on some systems is a example of a kexts that may make your system to not boot.
Giorgio Multi post found here
Wiki post found here
Edited by p.H and Rampage Dev
Method 1: Mac OS X Using Single User Mode
Part 1: What Is Single User Mode
Single User Mode is different from a Safe Mode boot in that the system goes directly to the console instead of starting up the core elements of Mac OS X (items in /System/Library/, ignoring /Library/, ~/Library/, et al.). From there users are encouraged by a prompt to run fsck or other command line utilities as needed (or installed).
Part 2: How To Boot Into Single User Mode
1. Record the kext you wish to remove
2. At the boot loader prompt screen type in the following:
3. Press Enter
4. After the system loads a blinking cursor will appear. This indicates that you may start typing in commands.
5. Replace name_of_the_kext.kext with the name of your kext you wish to remove
6. Type the commands below, press enter after finish entering each line:
mount - uw / cd /System/Library/Extensions rm -rf name_of_the_kext.kext sudo rm -rf /System/Library/Caches/* shutdown -r now
Note Make Sure That The Spaces And Casing In The Text Is Correct
7. The kext should now be removed
Method 2: Using Windows Or Other Operating System
You can remove a kext by using macdrive or other programs which allow you to access the OS X partition. All you need to do is just delete the entire folder of the kext. (kexts are displayed as folders on windows or other OS)