This should not normally be needed...but in my case it was. YOU WILL LOSE ALL DATA. THIS IS NOT A TRIVIAL PROCESS.
If you need to remove Voodoo4, for whatever reason (mine was not booting), this is how you do it:
1. Download original.mbr from here:
http://adrynalyne.us/files/kernels/sgs/original.mbr (right click save as....)
2. Download stock kernel:
2. Boot to cwm (battery pull, and hold up volume while putting it back in and connected to usb), and put original.mbr and stock.zip on your sdcard. Mount as mass storage or adb push them to sdcard.
3. Use adb to restore the mbr:
cat /sdcard/original.mbr > /dev/block/mmcblk0
5. Mount dbdata and nuke the contents.
mount -t rfs -o nosuid,nodev,check=no /dev/block/stl10 /dbdata
rm -f /dbdata/*.*
7. Apply CWM. Wipe data.
Done and done. Nandroid restore back after this, if you wish.
If this doesn't work, take the illogical steps of:
Flash system, kernel and PIT with Odin. Remember, only use pda and pit sections.
I am adding the uninstaller again, but it is not perfect.
To use the uninstaller, DO NOT USE ROM MANAGER!
1. Boot clockwork, and apply the uninstaller.
2. Go to the advanced menu and choose reboot recovery.
3. Wipe data from stock recovery. Apply CWM. Wipe data from clockwork.
4. Reboot phone.
Voodoo Uninstaller DI01 ONLY
1. Disable voodoo either by adding a disable_lagfix text file or folder to /sdcard/voodoo directory, or by using the RED clockwork recovery for voodoo and going to the voodoo menu. Remember , you can only boot to it via:
adb reboot recovery
manually (hold volume+/- and power)
Rom Manager cannot boot it.
2. Once disabled, flash a nonvoodoo kernel.
If red clockworkmod remains, please flash this, then reflash your nonvoodoo kernel of choice.
Thanks jt1134 for kernel, and pii for bringing the issue to my attention.
Flash via PDA in Odin. This will return you COMPLETELY to DI01 stock, bloat and all. You will need to reroot, etc.