You can't Tamkfan, you've misinterpreted what dUKE has said.
He is saying how it would be a good idea to let reviewers delete their reviews. It's currently not possible, but may be in the near future.
I personally am behind the idea, as this will allow users to 'try again' with their reviews. I am seriously contemplating re-doing my earlier reviews of Sims 2: Nightlife, Wild Arms 3 and Armoured Core 3.
NOTE: This is not a message to staff that I want those reviews deleted. I am still considering it.