I am uploading a file is SP 2010. But, uploading there is property dialog comes up that contains the "Content Type" combo. I want to remove unnecessary content types from it. How to do this ? Thanks
If I understand the question correctly, you want to remove content types associated with the document library.
To do this, go to List Settings -> Advanced Settings -> Set 'Allow Management of Content Types' to 'Yes'. Then go back to list settings, you should see a list of content types under content types section. Click on the one you want to remove and you should see a link that says 'Delete this Content Type'.