Instructions apply to the Messenger app foriOSandAndroid.
Messenger is also available for Windows 10 or via a web internet tool.
Here’s how to set up a group in Messenger and start a chat.

Open Messenger and tap thenew chaticon.
In a web client, click theFacebook Messengericon at the top of any Facebook page.
TapCreate a New Group.

Select people from your friend list to add them to the group.
Give the group a name.
(This is an option for groups of three or more.

you’ve got the option to change it later.)
Here’s how:
fire up the group in the Messenger app.
Tap thegroup nameat the top, then tapMembers(tapSee Group Membersin newer versions of Messenger).

choose the friend you want to remove.
New members can see all the past messages sent within the group.
initiate the group you want to edit.

Select theplus signand choose new members from your Friends list.
Here’s how:
pop crack open the group you want to leave.
Scroll down and tapLeave Group(orLeave Chat).
TapLeave Group(orLeave Chat) to confirm.
If you’re leaving a group you created, you could set a new admin.
If you don’t, the first person you invited who is still in the group becomea the admin.
Leaving notifies the other members you’ve left.