Just to make sure, you don't want your NTFS there anymore? I'll gather that's what you mean by rewrite partition.
You only have write for a very very good reason, that's all that the kernel drivers support safely (and writing over a file without changing it's size lately too)
Just start up your favourite mkfs.<blah> to make yourself a new parition. (like mkreiserfs, or mkfs.ext3, so on)
If it tells you to delete the partition you had before, use fdisk to do so (man fdisk), or get cfdisk, which has a nice graphical frontend for the commandline-flag-shy. I've never had an NTFS parititon to convert, so I don't know any specific issues, this should definitely work though.
The issue with write permissions is just to the partition data itself, you can do anyhting to a disk as root