How to use "neither" in second-person plural?
There is nothing you can put into the exact sentence you have that makes sense.
If you have to use I as the subject and use the word neither, your only choice is to rephrase the sentence.
You could say:
I taught neither of you.
I was a teacher to neither of you.
I had neither of you as a student.
You could even do something with multiple clauses (although it sounds a bit odd):
You each had a teacher, but I was neither of yours.