Is anyone aware of how to do this? I was court ordered to not email someone negatively or instant message and have reason to believe they are making emails up and IMS with my id all to hold me in contempt and get me arrested, Please if anybody can, tell me how to cancel my ID!!

In this case simply go in and change the password to your account if you think it's your being hijacked. It's possible that someone created a new Yahoo ID that closely resembles yours for mischief purposes, there's not much you can do about that except make the authorities aware with some evidence to back it up.

Yahoo does not cancel accounts. So change the password and just stop using it. They will need to produce the header of any e-mails which can show they didn't originate from your IP.