Ubuntu 15.10 screenshoot HQ my desktop

iStyle bottom dock :D

How to disable user in ubuntu? How to delete (remove) guest user in ubuntu?

Step 1.
First of all we need to sing in as superuser!
(if you have already superuser password you can go to step 2)
 sudo passwd 

Step 2.
 sudo su 

Step 3.
deleting user just by typing simple terminal command
 sudo userdel guest