#To delete the column without having to reassign df
df.drop('column_name', axis=1, inplace=True)
df = df.drop(['B', 'C'], axis=1)
#to drop by column number instead of by column label, try this to delete, e.g. the 1st, 2nd and 4th columns
df = df.drop(df.columns[[0, 1, 3]], axis=1) # df.columns is zero-based pd.Index