I currently have a dual-boot setup with Ubuntu and Windows. Now I would like to remove the Windows partition which is 150GB and install Fedora 14.
In other words, I want to be able to dual-boot Ubuntu and Fedora.
One of the tools you will want to look into is GParted, which is a powerful partition manager for Linux.
Assuming you installed Windows before any of the Linux partitions, you will need to do some moving around to get things working the way you describe. The best way to do this is to boot from the Ubuntu LiveCD (which includes GParted) and run it from there. (The reason being that you cannot modify partitions that are currently active (In most cases, anyway).)
Once the tool is started, you will be able to see all of the partitions on your disk and manipulate them as you see fit.
Here is a screenshot of what the interface looks like:
Notice the keys next to the
In your case, assuming that you have backed up everything of importance on the Windows partition, simply remove it (it will probably be the first partition, with the NTFS filesystem).
Now you can expand your Ubuntu partition to take up the space freed by removing the Windows partition, and you can add room for the Fedora partition in a similar way.
If you want to keep your partitions the same size you can just use the Fedora installer and reformat the Windows partition.