I use Ubuntu 12.04 and have a dual system with Win7. Recently I also installed Ubuntu 13.04 so I have Grub giving me the choice of "Ubuntu" (13.04), Win7 and "Ubuntu 12.04". I want to uninstall 13.04, any hints? Thanks in advance.
Do you have the 13.04 installation disk? If so, boot from it, and check if the installation setup gives you the option to run the Ubuntu distributions side by side.