How To Change Default Admin URL in Magento

Make sure you can access local.xml file present in app/etc/local.xml.

Open this file in edit mode and look for below piece of code at the end of the file-

<admin>
   <routers>
      <adminhtml>
          <args>
            <frontName><![CDATA[admin]]></frontName>
         </args>
     </adminhtml>
  </routers>
</admin>

change [admin] to anything you like. Save and close the file. Clear cache

Go to browser and type http://www.your_website.com/your_admin_path.