Document Library - Content Types - filter Content Type dropdown when uploading document

Hi,

I create a document library, site columns and site content types with code and add the content types to the document library.

But, when I upload a document to the library, when the metadata form pops up, the drop down list for Content Type is populated with the OOTB Document CT and my two custom CTs. I want to show only one of my custom CTs and no Document CT.

How do I do this using C# code?

Thanks!