By default, anyone who can communicate with one of the people in your organization using Skype for Business can also see whether that person is online. Skype for Business shows whether a person is available online, in a meeting, offline, or another indicator.
As the admin for everyone in your business, you can choose who sees their online presence in Skype for Business.
Go to Office 365 admin center > Admin Centers > Skype for Business.
In the Skype for Business choose organization.
Under presence privacy mode, select one of the following settings, and then choose Save.
For information about what your users can change in Skype for Business, see these articles: