Function enif_make_map_remove 

pub unsafe extern "C" fn enif_make_map_remove(
    env: *mut ErlNifEnv,
    map_in: ERL_NIF_TERM,
    key: ERL_NIF_TERM,
    map_out: *mut ERL_NIF_TERM,
) -> c_int

See enif_make_map_remove in the Erlang docs.