Group Policy Objects are used in a domain for a variety of purposes. Usually you use the built in templates to accomplish what you want but occasionally you will need to alter the registry to get the task done.
You will want to open Group Policy Management on your domain controller. Right click the OU you want and select "Create a GPO in this domain and link it here"
Once the Group Policy Management Editor is open you will drill down.
You can also do the same under "User Configuration" if you want the effect whenever a user logs into the machine.
Here is an example of how to prevent Skype for Business from opening when a user logs in:
Now when a user logs in Skype for Business / Lync will not automatically open.