Manage group invite settings
Navigate to the group you want to manage.
Click on Group settings and then select General.
Toggle the People can join this group setting — People can join this club at the top level to either on or off depending on your preference.
On: Allows new members to join using the group code.
Off: Prevents new members from joining using the group code.
Generate a new group code
If you want to stop users from using the old group code to join:
Go to Group settings and select General.
Locate the group code section.
Generate a new code with Generate new code.
This will invalidate the old code, ensuring only the new code can be used to join.