Installed CPUFREQ and computer will not boot to OS

[Rapidrob]

I did a stupid move. I downloaded CPUFREQ and open it up. My Quad core was set to 1.6 Ghz but is rated at 3.4 Ghz and shows this as a select-able option. I changed to the faster freq and now the computer will not boot to the OS. Grub screen is there but there is no RESTORE option to go to the backup HDD.
I can mount the primary OS HDD in an external reader. Is there any commands with steps on how to do it, to remove this CPUFREQ software from my HDD on the external dive?
Please help if you can.
Thank you.