Created bootable .iso on external USB HDD, how to get rid of it again?

Question

Using the guide on ubuntu.com I installed the image of the netbook edition on my external HDD using Pendrive on Windows. I was not aware that it would create such a mess and now want to get rid of it again, still retaining my old files. How can I do that?

Answer 1

If I'm not mistaken, the USB installer adds some files in the root folder of the USB disk and makes it bootable by adding some code in the Master Boot Record.

You can safely remove the files created by the USB installer using the Delete button.

You can restore (read: clear) the MBR (Master Boot Record) using the following command:

sudo dd if=/dev/zero of=/dev/sdX count=1 bs=512

/dev/sdX is your USB drive, if you run ls -l /dev/disk/by-label, you will labeled partitions, e.g.:

lrwxrwxrwx 1 root root 10 2011-03-04 22:58 ubuntu -> ../../sda1
lrwxrwxrwx 1 root root 10 2011-03-04 22:58 USBDRIVE -> ../../sdb1

Here, you can see that /dev/sdb is the external USB. If your partitions are not labeled, you could use sudo fdisk -l to get a list of partitions for each drive.

For relabeling the partition, you can use GParted, see How can I relabel my flash drive?.