How can I get a temporary crown/cap off by myself? (Photo)

It's hurt since day one almost five years ago only the last few days it took a turn for the worst. It feels like child birth in my mouth. I can't eat, I can't sleep, it's hard to talk. I no longer have any dental insurance and I cannot afford to go to the dentist. She said the tooth under it was in bad shape and she had to build it up. How can I get this thing off by myself? Please help!