How about a WRENCH??

An Allen wrench.

Michael

do you have a rachet set ,from the pic it looks like a 5/16 socket should work.mabey smaller/bigger.

Out of desperation I'd probably use a small needle nose plier.

If your asking about the fastener on the back plate beside the text in the photo, that is not a screw, it is a hex head nut.

To remove a hex head nut you would use an open or closed end spanner wrench, adjustable wrench, socket wrench, nut driver or channel lock pliers.

If you are asking about the two dowel pins in the foreground, they appear to be either press fit or spot welded in place and would require cutting off flush with the base material, then either grind smooth or drill out the hole.

Use a nut driver or a small socket wrench. It looks like about a 5/16.
http://www.sears.ca/gp/product/B000FJG9DS?searsBrand=core

If you are asking about the two dowel pins in the foreground

That's funny. It's an optical illusion. I didn't see two dowel pins sticking out, I saw two indents in the metal. I didn't know what you were talking about. Had to look at the picture again. Now I can see it both ways, but I still think they are really indents.