Sorry for the delay in responding to your question.
So – I did the exact same thing. Here in Alaska the incorporation process is so easy I missed a heap of stuff the IRS wanted to see.
The only way to fix it was to ammend my articles. It is actually a pretty painless process. I struck out what I didn’t want and added what I did want. Paid a small fee. Waited a couple weeks. And it was done.
Ammending is an official process that has to be documented. It is, as far as I know, the only way to update your Articles of Incorporation.
I will forward your question to our resident expert (Tom Wrobel – nonprofit lawyer) and see if he has anything to add.
Nonprofit Ally Founder/Admin