Manually Remove Plugin (When FTP Won't Let Me)

Ive installed wordpress on a clients server, which is Windows. I developed the theme and had everything working beforehand on a linux server. Upon setup on Windows, i couldnt seem to get Nextgen Gallery working properly..getting a rewrite error desipite all other aspects of rewrite module working fine. So…i decided it probably had to do with permalinks, but i could seem to reset them. so i clicked the button with nextgen to completely uninstall the plugin. Then tried to remove it. Trouble is, the folder is still there. With only “admin” and “fonts” left inside it. I went in with FTP but im unable to delete or change the name of the director. When i try to reinstall nextgen, i get a fatal error. Any help would be greatly appreciated.