I have a question about deleting columns after grouping Python Pandas data.

%matplotlib inline
import numpy as np
import pandas as pd
import matplotlib as mpl
import matplotlib.pyplot as plt
import os

data_filename = 'Popular_Baby_Names'
data = pd.read_csv("C:/Anaconda3/DataSet/Popular_Baby_Names.csv", index_col='Gender')

data2 =data.rename(columns={"Year of Birth":"YoB"},inplace=True)
data2

groups = data.groupby(data.Ethnicity)
groups
groups.sum()

del data2["Rank"]