removing ubuntu 12.04

I have ubuntu 10.04 and 12.04 installed on my computer. Now I have decided that I don’t want 12.04 and want to remove it.
I have tried startup manager and Grub2, to no avail. When I start the computer I still have to scroll down past 1.04 to load 10.04.
I am a beginer with ubuntu and would be happy with any assistance anyone could give me.

The best way would be to use Gparted from a LiveCD to -

a) delete the 12.04 partition(s)
b) resize the 10.04 partition(s)

then reinstall the GRUB bootloader.

Have you got a 10.04 LiveCD/LiveUSB ?

What’s the output from:

sudo fdisk -l

If it’s the Unity desktop you don’t like, I’d be more inclined to change desktop environment than to ditch 12.04 in favour of a version that is no longer supported.

If that’s not the reason … can I ask why ?