Double installation how do I delete one

[marvin.phythian]

Hi a friend of mine bought a laptop and her son changed and forgot the password, I read that I needed to reinstall all the software using original installation disks I did that but it hasn't got rid of the old one so now there is no memory how can I fix this?

 

[johnb35]

You basically did a new installation along side the old one. Your best bet would be to backup any data needed and do a fresh install of the Operating System now. You would have to delete the existing partitions and then repartition and install.