Fun with idiosyncratic speech behaviors

Is there a name for a phonological process in which a child consistently reduces an entire word to just a vowel? For example, the word "Six" becomes /I/. The word "three" becomes /i/. Also, is there such a thing as "consonant cluster deletion"? Not reduction, just straight up deletion of any consonant cluster? Seeing some very odd things here.
yup. agreed ^ (of course...based on such limited information, that'd be my hunch!)
Yup! CAS! Otherwise, maybe a severe phonological processing disorder with initial AND final consonant deletion.
my school is so conservative about the CAS label (even casually speaking about it)! i can hear a professor saying "call is a severe speech sound disorder".

not a phonological process, an idiosyncratic behavior of a severe speech disorder... :)
There is most definitely a consonant cluster deletion process. It is possible to have a severe phonological disorder without it being CAS. I've had several kids who basically had vowels only, but weren't CAS. The most recent one was in kindergarten - and had never been seen in tx before.

Is there groping behaviors, are the errors inconsistent? Are the vowels wrong? Those are indicators of true CAS.

Deletion of consonants - that's typical phono (if there's such a thing).

One of the things to look at when kids are deleting initial consonants - is there VPI issues? Any signs of a submucous cleft?

If those are fine - and there's not many CAS indicators, I'd treat as typical phono. I love those kids. Give me someone with just vowels anytime over a lateral lisp or an /r/. :)