People join a group in one of two ways: by typing its code, or by opening its invite link. Both live under Group settings > General, and one toggle turns both off.
Turn joining on or off
Go to the group and open Group settings > General.
Find People can join this group. At the top level of the organization the same setting reads People can join this club.
Set it to On to let people join, or Off to stop them.
Turning it off closes the door to new members only. Nobody already in the group is affected.
Share the code or the link
A group has both, side by side on the same page:
Group code — a short code somebody types in themselves. Copy code puts it on your clipboard. If the group has no code yet, Create an invite code makes one. At the top level this is the Club code.
Group invite link — a URL that opens the join flow directly, so nobody has to type anything. Copy link copies it. At the top level this is the Club invite link.
Replace a code that has spread too far
Anyone holding the old code can keep using it, so a code that has been forwarded past the people you meant needs replacing rather than hiding.
In Group settings > General, find Group code.
Click Generate new code.
The old code stops working as soon as the new one exists. Anyone who has not joined yet needs the new code, or the invite link.
Let players sign up without a parent
Allow player signup sits on the same page and is a separate decision from the join toggle. With it On, a player can create their own account and join; with it Off, a player needs a connected parent.