nápověda přímo z programu:

There are many ways to uninstall GAG:

From Linux
Just install GRUB or LILO in the MBR. It will overwrite GAG.

From Windows
You can use any program which restores the original MBR, like MBRFIX.

From the installer
If you have a boot floppy or boot CD-ROM with the GAG installer, just boot with it and use the option 5 (uninstall GAG). It will put in the MBR a standard code. Use this if you can't use the previous methods.