Remove bookmark/reading list/link column in safari on ipad
Tap the blue highlighted book icon next to the address bar.

A clarification:  Tap the book icon directly to the left of the address bar (on my iPad this book icon is white; not blue) Do not tap the blue book icon that is located on the reading list itself (nothing will happen when you tap the blue book icon on the reading list itself). 

If you do not see the book icon to the left of the address bar, tap the grey bar at the top of the page (where you see the time, battery level, the word 'iPad', wifi symbol) and you will then see the address bar.  The book symbol is immediately to the left of the address bar. Tap this book symbol and the annoying, large, reading list box will disappear.