You can't completely close an account on the blockchain. You can power down your stake there and liquidate, or sell it. You have about $20 worth in your wallet... so you could begin the process of undelegating and powering down. We will be started to execute the actions mentioned in this post fairly soon since it's been a month or two of opportunity for people to make their choices.

I didn't see that you were active other than curation rewards etc. So, you can just drop off or cash out over there. That's really the closest one can get to closing an account.