If you are a Website Owner, Reseller, Root Administrator, or Data Center provider, you will have different levels of access so you will need to try the following to find your cPanel version.
In cPanel, you can find the version on the left-hand menu under Stats in the default X3 theme. Please keep in mind, you may have to click on the ‘Expand Stats’ link first. In the Paper Lantern theme, scroll all the way to the footer of the page the see the version number. You can also look for the ‘Server Information’ link which will list more information in the right-hand menu.
Footer: cPanel, Inc. 70.0.27
Server Information: cPanel Version 70.0 (build 27)
If you are given access to WHM, you can find the version number at top right hand corner of the page. Since it is in frames, it is always viewable. Clicking on it will give you the option of installing cPanel again or doing an update.
CENTOS 6.9 Virtuozzo [host] v70.0.27 Load Averages: 0.41 0.36 0.29
If you have Root SSH Direct Access, running cat /usr/local/cpanel/version will display the version number.
/$ cat /usr/local/cpanel/version