instale las version nueva y quiero desistalarla

Have you tryed in the software center?

1-via netwoek
In a terminal (Ctrl+Alt+T), run command:
   gksudo update-manager
Uncheck "Upgrade only to LTS version".
A button "upgrade to xx.xx" version will appear. I presume it will be 10.10, as you can only upgrade only from one version at each step.
As you will do 10.04.3 -> 10.10 -> 11.04 -> 11.10, it will:
- take a lot of time
- have a probability to fail,
so I advice:
2-via CD
Make a backup of /home and other user files (in theory, will not be used later...)
Download ISO image of Ubuntu.
Boot on Ubuntu media
Choose "Manual partitioning"
Mount "/" folder on ext# partition.
DON'T format.
Continue the installation.
Check it worked.
11.10 is supposed to:
- keep user files in /home
- replace system files in other folders

Don't hesitate to request more information.

No I did not think of that.  I will try it when I get a moment and let you know.
Thanks

________________________________
De: Ibai <email address hidden>
Para: <email address hidden>
Enviado: lunes, 7 de noviembre de 2011 10:30
Asunto: Re: [Question #177924]: How do i upgrade from 10.04 to 11.10

Your question #177924 on yelp in Ubuntu changed:
https://answers.launchpad.net/ubuntu/+source/yelp/+question/177924

    Status: Open => Answered

Ibai proposed the following answer:
Have you tryed in the software center?

--
If this answers your question, please go to the following page to let us
know that it is solved:
https://answers.launchpad.net/ubuntu/+source/yelp/+question/177924/+confirm?answer_id=0

If you still need help, you can reply to this email or go to the
following page to enter your feedback:
https://answers.launchpad.net/ubuntu/+source/yelp/+question/177924

You received this question notification because you asked the question.

If you want to upgrade instead of clean install you will need to upgrade to maverick first. If you can wait til October, you can jump directly to Precise (12.04) in one jump.

https://help.ubuntu.com/community/UpgradeNotes
https://wiki.ubuntu.com/OneiricOcelot/ReleaseNotes

https://wiki.ubuntu.com/PrecisePangolin/ReleaseSchedule

Also note that Oneiric will look a whole lot different from 10.04
https://help.ubuntu.com/11.10/ubuntu-help/index.html
https://wiki.ubuntu.com/PowerUsers/Tweaking