If you've already paid in that much, it's too late to quit. This endowment plan will give you back $9k if you quit now, but it is guaranteed to give you back $18k if you quit 15 years later. If you quit now and take that $9k, do you think you can turn the $9k into $18k in 15 years? You would need to generate a 4.75% return per annum to achieve that, and that's not easy unless you get yourself educated on how to invest first. And even then, even people who are great at investing, would think twice before giving up on a virtually risk free (prudential is a blue chip company with low default risk, and the policy is further insured by the SDIC. Chances of default is incredibly low) guaranteed 4.75% return with a 15 year lock-in. If you're not savvy about investing, it's better to just leave the amount there at this point. Heck, if you still insist you want to surrender it, let me know, and i'll buy the policy off you at a higher price then the surrender value.
If you wanted out, you needed to get out in year 1. It's too little too late now. Take it as a lesson learnt to never buy another endowment plan. Rule of thumb: If you meet an investment agent, and the first thing they try to sell you is an endowment or ILP, tell them to screw off. They do not have your best interests at heart.