how to remove windows partition in boot camp..

i used to try to get windows in my mac..but it was failed..and i wanna remove it..
now..i have been trying to remove the windows partition for a year..i still cant do it..

it comes up like this..



how do i solve it?

thanks..

Welcome to Mac Forums.
Hold down option key when you boot at the sound of the chime, and select Macintosh HD.
Then go to Bootcamp assistant, click continue at introduction window, then select create or remove a Windows partition, click restore to remove the partition.
If this doesn't work for you, try to boot from your OS X install disk holding C key down as soon as you hear the chime, and when it boots, select language and then go to utilities/disk utility in the menu bar.
Then drag the right bottom corner of your Macintosh HD partition out to the bottom.

when i click "continue"..it can't go for the next step which is "create or remove" step..