Start of by deleting your lab environment in Cloud Lab.
After deletion, Create a new Cloud Lab.
Open terminal as root and run following command
curl -fsSL rhce.botweb.online/setup.sh | sh
Once done, click on Start button.
Note: Once you click on start button the exam will start. On the top left of the page you can see the timer for 4hrs. Once timer is finished the exam will end and questions will be locked.