Note that this reference documentation is identical to the help that is displayed in MATLAB when you type “help rmsubfield”.

  RMSUBFIELD removes the contents of the specified field from a structure
  just like the standard Matlab RMFIELD function, except that you can also
  specify nested fields using a '.' in the fieldname. The nesting can be
  arbitrary deep.
 
  Use as
    s = rmsubfield(s, 'fieldname')
  or as
    s = rmsubfield(s, 'fieldname.subfieldname')
 
  See also SETFIELD, GETSUBFIELD, ISSUBFIELD