Here is how I do this with just one mouse click (OK, maybe two :):
You can change the layout of the thumbnail view pane. Make sure that you see two columns of pages:
You can change the size of the thumbnails using the size control (I've marked that with a red box).
Now you draw a selection rectangle around the column on the right to select all even pages:
Once the pages are selected, just hit the delete key and these pages will be removed (after confirming this action):
You can select more pages than are visible in the thumbnails pane: When your mouse hits the bottom of the window, the view will start to scroll. It gets a bit complicated if you have a large number of pages, in that case, you may want to use a JavaScript action, but for smaller documents this is the best and quickest way to delete every other page.
By changing the layout in the thumbnails pane, you can also delete every 3rd page, or every 2nd and 3rd page... The options are endless.
Karl Heinz Kremer
PDF Acrobatics Without a Net
PDF Software Development, Training and More...
http://www.khkonsulting.com