Step 1:
To reboot your virtual machine, go to the client area, and click the "My Services" tab;
Step 2:
You then need to expand the product you wish to reboot; Click on the View Details.
Step 3:
Scroll down to the bottom of the VPS you selected and as shown below, you should be able to see the following menu:
Step 4:
This will allow you to reboot, power off and stop the VPS.