Compare two dataframes and export unmatched data using pandas or other packages?

I have two dataframes and one is a subset of another one (picture below). I am not sure whether pandas can compare two dataframes and filter the data which is not in the subset and export it as a dataframe. Or is there any package doing this kind of task?

The subset dataframe was generated from RandomUnderSampler but the RandomUnderSampler did not have function which exports the unselected data. Any comments are welcome.