Honestly, the time writing this question and waiting for an answer, is longer than just going into screen options, setting the posts to about 200, and just doing bulk move to trash, and emptying the trash – if you speed is high, you can probably do even more than 200.
else there is a nice tutorial on how and which tables you should work with here – but it will probably take longer
http://www.tripwiremagazine.com/how-to-effectively-bulk-delete-many-posts-in-wordpress/