Hi Sally,
You have to enable the User inventory to gather the information.
1. Go to Manage->Policies->Discovery and inventory->Create a New inventory policy as shown in the screen shot
2. Then check the report
https://www.symantec.com/connect/sites/default/files/2016-06-22_23-50-33.png
3, In Database you can able to find in the below tables
Inv_UG_User_Account
Inv_UG_Group
Inv_UG_admin_Group_Members