/gprivate
Either claim an unclaimed storage, or change it from public to private (if you own it).
Just look at a physical container storage and call the command
/gprivate
If that storage currently is unclaimed (Unregistered):
It now becomes Private.
You are now its owner.
No one can break it nor access it except you.
If that storage is currently Public:
You must be its owner already to use this command.
It becomes Private.
Only you will be able to access it now.
Only you and people you manually add will be able to put items into this storage, and take them out.
Only you are able to break it.