How to remove the favorites appearing on the left side of the screen in Safari-El Capitan?

I almost always use Safari on the whole screen mode, which I love. However since I updated to El Capitan, each time I move the mouse to the left side of the screen my favorites or lecture list appears. This is very annoying as for some websites I frequently visit I unintentionally place my cursor near there. Does anyone knows how to remove the favorites/lecture list from appearing on wide-screen mode? Thank you in advance.