Similar to the myriad uses of the term 'phase', the terms 'wye' and 'delta' have several uses in the industry. Look at the original post, where the MCC is described as 'setup as a delta'.
As used to describe transformers, wye means one sort of winding, delta means another sort of winding. 'Zig-zag', 'Scott T', etc. describe yet more esoteric windings.
Wye and delta are also used to describe _services_; a wye service is a three phase service that has a neutral point that is at the 'center' of the three 'phase' voltages. A delta service does not have this neutral point; it may have a 'center tap' on one of the side legs.
Suitably connected, a transformer with a wye secondary can provide a delta service. So could a transformer with a zig-zag secondary or a T secondary.
Suitably connected, a transformer with a wye secondary can provide a wye service. So could a transformer with a zig-zag secondary or a T secondary or even a transformer with a delta secondary in combination with a separate zig-zag transformer.
I agree with Charlie B that the description of the inner workings (which might require a sawzall to determine) is what it is; a wye secondary doesn't suddenly become a delta secondary just because of its external connection. However a wye secondary can supply a delta service.
Back to the original post: this 'neutral' conductor that was brought to the CT cabinet, was it grounded at the transformer or CT?
-Jon