No its not about dual booting, xe creates a second boot entry to emulate slic with an alternate method after the default emulation. So you only need to reboot into that xe option then after another reboot it'll be gone, so a total of 2 reboots. BTW you reformatted/reinstalled the OS ?
Did you reboot into that xe option after reformatting/reinstalling OS ? After you boot with that xe entry it runs the loader again from a temp folder to emulate slic with an alternate method so if xe isn't present in that directory the boot entry might not be removed, have you tried to remove it with boot repair/recovery console ? If so perhaps the only option you have is to reinstall the loader whereby it'll overwrite that previous xe entry & then boot with that option once to have it removed from your boot menu. Try this method only if all else fail ! There is one other way I can think of - run Yamicsoft win7 manager & look for boot configuration under customization tab, here you can delete unwanted/unnecessary boot entries.
Have you installed win7 from a genuine medium(original/untouched) or was it preinstalled ? The only reason I can think of is that loader somehow ran before you booted i.e. xe was there in the installation media or it was there on your preinstalled system.
I think you should try out win7 manager before you go through the hassle of reinstallation/reformat. DAZ loader or remove WAT would be my picks.
Check the windows7(other boot) option as the default boot entry then delete the xe entry otherwise it won't work !
Quite right - use Yamicsoft as you described. Be sure to turn off your internet connection before you install Yamicsoft and use the keygen. Exclude this keygen from your malware scanners. Even turn your malware scanners off while you use the keygen. You have to use a trusted source for all this of course. It's your risk.