how to drop the index column in pandas

df.reset_index(drop=True, inplace=True)

cols = [1,2,4,5,12]
df.drop(df.columns[cols],axis=1,inplace=True)

>>> df.reset_index(drop=True)
    class  max_speed
0    bird      389.0
1    bird       24.0
2  mammal       80.5
3  mammal        NaN

 df.to_csv(filename, index=False)