Open Finder and navigate to ~/Library/Application Support/Skype/.
The “~” sign means your home folder. To find your home folder, open Finder and in the main menu, select Go > Home or press Command (Apple) + Shift + H keys.
It is the folder that has your Skype Name.
An app restart may be required after making modifications.
Also, try this location:
/Library/Application Support/, as there is a difference when the tilde sign is used.
Furthermore, the stores file can be found in
~/Library/Containers/com.microsoft.SkypeForBusiness, which is the user folder according to This Post