You cannot move anything beyond the border of the slide, unfortunately. Lectora announced that it'll be available in Lectora 12, which is coming out in 2015 (I think).
But you can achieve what you want using scripting. Are you savvy with JavaScript and CSS?
UPDATE. You can achieve this with just a couple of actions. Basically, just set it to initially hidden, then on click, move it off screen, then make it visible, then move it back in. Voila.
Live demo: http://intea.lv/files/trivantis/offscreen/
