Open skitter.styles.css and change this line display: block;
to
display: none !important;
In skitter.styles.css,
/* =Round theme
-------------------------------------------------------------- */
.skitter-round .prev_button,
.skitter-round .next_button,
.skitter-round .play_pause_button,
.skitter-round .focus_button
{
display: none !important; // change to this
background: url('../images/sprite-round.png') no-repeat;
}