How do I add/remove people from my group?

Unless Restrict  Membership has been set by the Group Admin, anyone in the Group is able to add or remove members within the Group. 
To add or remove a member:
  1. Tap on the three dots next to the group chat tile
  2. Select Edit Group
  3. Here you'll see a list of your group members. Tap Add Person to invite new members to your group
  4. To remove a member, tap on their name, then select Remove from Group