removing legacy raid settings from a drive

[Gregory Machin]

Hi
I have a drive from a software raid set that I'm trying to reformat.
When I try and reformat it i get the following results

[root at ns ~]# mkfs.ext3 /dev/sdc1
mke2fs 1.41.4 (27-Jan-2009)
/dev/sdc1 is apparently in use by the system; will not make a filesystem here!

I see the drive has been marked as being raid from this.

[root at ns ~]# cat /proc/mdstat
Personalities :
md_d0 : inactive sdc1[1](S)
      244195904 blocks

unused devices: <none>


How do I remove the raid association so I can reformat it ?

Thanks
G