[GParted] is a powerful HDD partition editing tool. Use it to make/delete/resize nearly any file format. GParted is available in the extra repo and also as a [Live CD] if you'd prefer. One reason to actually download the Live CD would be that you need to make modifications to your root filesystem's partition which you cannot do without it.
GParted is in the extra repo as mentioned above, to install it simply use pacman as you would with any other arch package
# pacman -S gparted
The base gparted package doesn't come with support for all filesystems. Here is a brief list of additional packages you can install to add support for different filesystems:
e2fsprogs: for ext2/ext3 partitions dosfstools: for fat16/32 partitions jfsutils: for jfs partitions ntfsprogs: for ntfs partitions reiserfsprogs: for reiser partitions reiser4progs: for reiser partitions xfsprogs: for xfs partitions