When the Ubuntu kernel is upgraded, the older versions are still shown in the GRUB boot loader. These can easily be deleted from the boot loader, leaving only the newest kernel and any other operating systems that are on the machine.
- Open the Terminal (Applications>Accessories>Terminal)
- Type: sudo gedit /boot/grub/menu.lst, then press Enter
- Enter password if asked, then press Enter
Find the section that says: ## ## End Default Options ##. Here it will show all of the entries that are on the GRUB boot loader. Just delete the older entries that will not be used anymore. The newest kernel version is usually listed first. Save the changes and exit the Terminal. When the system is rebooted, the deleted entries should be gone from the boot loader.
The default operating system will also have to be changed now. The instructions are here.
