Unable to disable Composite models

I figured out the issue. Even though all of the tables in my model were marked as Import, I had created bi-directional relationships that wouldn't be allowed in the model if the "Composite Models" feature were disabled. Since I had the relationships established and the  composite model option enabled, I was unable to publish to Power BI. Once I disabled the composite model option, the relationships remained and I was unable to re-open the file unless I enabled the "Composite Models" feature. 

The issue here is that even if you have "Import" set for all of the tables, you can still create bi-directional relationships between tables that aren't valid. The final solution was to delete the relationships in the model, disable the "Composite Model" feature, restart power bi, and then re-establish the relationships (fixing the relationships that were invalid). 

Eric