How do I get this stuff off my computer?

My granddaughter, age 19, asked to check her e-mail on my computer. By the time she was through, there were 2 new icons for music, she had signed up to get voice mail on my phone apart from my answering machine ($14 a month charged to my phone), and it takes me 5 minutes to get onto the internet because before allowing me to sign in, I have to shut down her instant message, etc. Lord knows what else is going to be charged to me. She claims to have multiple personality disorder, therefore she's not responsible. I do not believe she has MPD, having had direct experience with the real thing with another family member. She claims that she doesn't know how to do this, so doesn't know how to get it off my computer. But it's there, all with her name attached. She is no longer allowed near my computer, but how do I get rid of it, and shut her out completely? She does not live with me, and I had not seen or heard from her since she was 10.