Need to uninstall corrupted Linux on multi-boot system

Using disk utility in System Administration is the good way, but not from working Ubuntu.
At boot, identify on which partition is failing Ubuntu.

Boot on Ubuntu CD and choose "Try" instead of "Install".
Then System->Administration->disk utility
Delete ext4 partition of failing Ubuntu.
If you see two swap partition, remove one of them.
Extend ext4 partition of working Ubuntu to use freed space.
Then reboot on disk.

If you re-installed grub2 with the new linux installation then you can just delete the partition with the broken install and resize existing partions to use the space.

If grub2 was _not_ re-installed with the second Linux install then it's possible that the grub2 configuration files are still on the first Linux partition. I suspect this is not the case however - default behaviour is to install a new grub each time, so the active config files are found on the latest partition.

Note that there is nothing completely safe about re-sizing partitions. It's highly advisable to backup data on affected partitions before starting the operation. A failure during the resize can result in lost data or even (in the worst case) a partition that cannot be accessed. A power outage or a hardware problem can land you in a world of hurt.

To resize the partitions boot off the LiveCD you used for installation (select "try Ubuntu") and then use Gparted to delete and resize partitions.

Disk Utility is OK for basic stuff and looking at SMART data on a disk, but Gparted has more features relating to partition management and is easier to use. One thing that you will need to be aware of is the difference between primary, secondary, and extended partitions. It's quite likely that the Linux partitions are secondary partitions inside an extended partition because that is also the default behaviour of the installer. It will be easy to resize the linux partition to use up the rest of the extended partitions.

If the partitions are set up correctly _before_ installation (or if you're only creating new partitions) then the installation process only takes about 15-20 minutes. It's resizing partitions and moving things around that takes up so much time.

Chris

Thanks Chris, that solved my question.

But on reboot after removing the partition, the system failed on reboot:
Error: No such partition. GRUB Rescue>

A Web search found a way to restore GRUB on the page: http://www.rajeshrana.net/2010/10/12/grub-error-no-such-partition-grub-rescue/

So everything works now -- however, the deleted Linux partition still shows on the GRUB menu. Not a big deal as I can ignore it, but if there is an easy way to clean up the menu I'd like to hear about it.

Thanks

Thanks marcus aurelius, that solved my question.