1. Make a backup copy of any important data on winduhs
2. remove the winduhs partition
3. if you have an entry to boot winduhs, edit your bootloader config and remove it
4. reformat the winduhs partition for something more suitable to Linux (ext2/3, whatever)
5. mount the old winduhs partition wherever you please
option 1: use a partition resizing tool to grow the linux partition over the winduhs partition (only possible if the geometry of your partition allocations happends to be favorable)
option 2: make an archival copy of your linux system on an external hd; 'cp -a' will do - then boot from a live CD, repartition the HD as you please, copy the archive back, and set up the bootloader. Thanks to 'udev', most of the links in the archived '/dev' directory may in fact be unnecessary - with the use of udev it's typical to only have 'console' and 'null' in /dev and the init script mounts a whole new set of device nodes over /dev before running udev - but variations exist between distros of course.