I'm trying to install Windows 7 with a 4GB flash drive, but my error that comes up is that my hard drive I'm trying to install on is in ext4. I need to format it to read NTFS. I can't seem to find any topics on how to format an active hard drive. I found a topic that explains how to move Ubuntu to a new drive, but it's a bit confusing to me.
So, I assume you are trying to format with ubuntu, and not wanting to keep ubuntu, so the best thing to do is to boot up to a live cd of ubuntu(most likely the disk you used to install ubuntu, if not Ubuntu download) and use gparted off the live cd, using gparted video, because you can't format the active partition while using it. Just keep in mind that formating the partition will get rid of ubuntu and all your data