I have cyst on ovary but don't want surgery. What other options are there? Its 6 cm.

Depends on cyst. If imaging shows a "simple" cyst, an option is to repeat imaging in 4-6 weeks to see if it is smaller or entirely gone. A "complex" cyst may require surgery, depending on its specific characteristics. Need for surgery also depends on the amount of pain you are having. If severe, you may consider surgery to definitively take care of the problem.
Try OCP. If there is no contraindications you can use ocp. Hopefully it will subside. Have another sono in 6-8 wks after therapy initiated.