This help looks normal:

1427:~/mypy/argdev$ python3 issue29626.py delete -h
usage: cli delete [-h] [-p] userid

Deletes a user in your organization.

positional arguments:
  userid             The userid of user.

optional arguments:
  -h, --help         show this help message and exit
  -p , --projectid   Specify the project ID of project from where you want to
                     delete the user or else user will be deleted from
                     organization.

So does this help for the nested subparser:

1430:~/mypy/argdev$ python3 issue29626.py nodes list -h
usage: cli nodes list [-h] [-p] [-o]

Lists nodes in your current project

optional arguments:
  -h, --help       show this help message and exit
  -p, --projectid
  -o, --org        (For administrators only) Lists all the nodes in

This double layered subparsers is not common, and might not even be included in the unittest file.  But provided you don't try anything too tricky it does work.  I've seen a few questions along this line on StackOverflow.

Note that the help line for '-p' in the second case is empty because you did not specify any help string (as you did for 'delete').