You must be an Administrator for this task
1. Click on the "cog" , select "Settings".
2. In the Users tab, click on the icon Filter
3. Click on Add a Filter.
4. Select from the drop down Verified is Unchecked.
5. Add a new filter to see only the Users that below to your Organization.
6. Click on the go arrow
7. Now you will see all the users that have not verified their accounts.