Jose,
If you mean can you hide the left or right panes, you can definitely hide the left pane using dojox.layout.ExpandoPane. It's natural movement is to close from right to left. For example, you can add the following before your dijit.layout.ContentPane div tag:
<div dojoType="dojox.layout.ExpandoPane" duration="1000" title="Hide/Collapse" region="left" maxwidth="325px;" easeIn="dojo.fx.easing.linear" easeOut="dojo.fx.easing.linear" style="width:325px;">
This will collapse your left pane. Just don't forget to declare the following: dojo.require("esri.dojox.layout.ExpandoPane") and dojo.require("dojo.fx.easing"). You could also add the splitter option to the end of the ExpandoPane which allows you to grab the edge of the pane and move it with your mouse. You can probably try that on the right side. The expandopane doesn't work as well on the right side due to the easing effects. Hope this helps.
