Ubuntu linux

I was trying to have dual boot with my system. I previously had Xp when I decided to installed ubuntu alongside. After installation, I realised that my Xp had some problem- some files were missing. I then decided to format and re-installed Xp. Then I couldn't see my ubuntu anymore. I was advice to defrag and installe ubuntu linux again which I did successfully. this time I have the dual boot fine. But my problem now is that the previous ubuntu i installed still appear and is like i have three boot option- 2 ubuntu linux and one Xp.. I want to get rid of one of the ubuntu.. Can anyone help me out please?