cannot remove column in pandas

1df.drop(['column_1', 'Column_2'], axis = 1, inplace = True) 

1#To delete the column without having to reassign df
2df.drop('column_name', axis=1, inplace=True) 

1df.drop(columns='column_name', inplace=True)

1DataFrame.drop(self, labels=None, axis=0, index=None, columns=None, level=None, inplace=False, errors='raise')[source]

1#to drop by column number instead of by column label, try this to delete, e.g. the 1st, 2nd and 4th columns
2df = df.drop(df.columns[[0, 1, 3]], axis=1)  # df.columns is zero-based pd.Index