Unable to delete Mailbox on iPhone 4S I have an iPhone 4S. Software 5.0.1

I have configured the Mail to GMail. Now, I want to delete the mailbox. Here is what I do. 


Click on the Mail icon
Click on Edit
Click on [Gmail]
Click on Big Red button called Delete Mailbox
Click on Delete Mailbox prompt 
I get an error message as below - 
Unable to Delete Mailbox. The mailbox could not be deleted on the server. 


I have tried it multiple times but to no avail. 

Any suggestions / thoughts?
[Gmail] and its children (Important, Spam, Starred) are not regular mailboxes (or tags, as internally used by Gmail), they are linked to specific Gmail functionality and therefore cannot be deleted. You can delete tags/mailboxes that you defined.