Convert pandas series datetime64[ns] to datetime

Question

I'd like to convert a series from datetime64[ns] to datetime. I read this and tried pd.to_datetime but it doesn't work.

example

import pandas as pd
from datetime import datetime
d = {'id': ['A', 'B'], 'date':[datetime.utcnow(), datetime.utcnow()]}
df = pd.DataFrame(data=d)
df.dtypes

id              object
date    datetime64[ns]
dtype: object

Convert date to datetime

df['date'] = pd.to_datetime(df['date'])

After converting, the dtype of date is still datetime64[ns]