I am working with Magento and found the secret key attached in admin url of magento. It is a unique key and used for security purpose. Its a Security protection provided by Magento. Its for Cross-site request forgery. You can search this work for more information about Cross-site request forgery. But if you want to remove secret key from Magento Admin Url than just follow below steps.
1. Login into Magento Admin Panel 2. Select System > Configuration > Advanced > Security 3. You can find Add secret key to URL 4. Select No from Dropdown & Save it. 5. You are Done.
Disable Secret URL From Magento Admin. You will not see unique string in Admin Url of Magento.