Can not delete Ubuntu partition after uninstalling Ubuntu

I insalled Ubuntu along side windows 7 , and then i removed it using the command prompt by typing the two commands ( i used windwos 7 DVD installtion disk)
bootrec /fixboot
bootrec fixmbr
and now when my computer starts it boots to windows 7...but when i try to delete the partition that contains the Ubuntu , it does not work, i use the disk management tools from windows, I've tried many times but every time i get the same message ...
is there any way to delete this partition from w7 or do i need to have third part software..
regards

and what is the message ???

Thanks guys for the reply, i am sorry i can not attach the message as i am away from home and can not access my PC, what you mean by '' reformat the partition to NTFS'' how can i do that

Mark Phelps , you are right when u've said That doesn't remove an Ubuntu install, instead, all it does is reset the MBR and default boot back to Windows 7. so i should delete the partition to get rid of Ubuntu

when I highlight the partition only delete is active others are inactive , and when i hit delete it does not work...