how to remove an emblem from a file?

[realsyy]

The first question is how to remove an emblem from a file?
I used the program interface called "caja_file_info_add_emblem" add an emblem to a file successfully,but there is no corresponding interface to remove it, what can i do to remove an emblem from a file?
The second question is the emblem added failed to display correctly, it meam whatever the emblem_name is,the emblem display the same,just like the picture following: