from datetime import datetime
d = datetime.strptime("10:30", "%H:%M")
print(d.strftime("%I:%M %p")) # outputs '10:30 AM'
d = datetime.strptime("22:30", "%H:%M")
print(d.strftime("%I:%M %p")) # outputs'10:30 PM'
df['Time'] = pd.to_datetime(df['Time'], format='%I:%M:%S %p').dt.strftime('%H:%M:%S')
print (df)
Time
1 17:21:26
2 17:21:58
3 17:22:22
4 17:22:36
5 19:18:16