Remove "checked"
Original:
<input id="mycheck6" name="mycheck" type="checkbox" data-dojo-type="dijit/form/CheckBox" value="agreed" checked onclick="updatePhase6Visibility(this);" /> <label for="mycheck6">Phase 6</label>
Updated:
<input id="mycheck6" name="mycheck" type="checkbox" data-dojo-type="dijit/form/CheckBox" value="agreed" onclick="updatePhase6Visibility(this);" /> <label for="mycheck6">Phase 6</label>