To add a new column
df['newcolumn']='new' + df['col1']
To remove a column
del df[df.columns[2]] <<aka>> del df['newcolumn']
Result
Result
To change column data type
df[['col1']] = df[['col1']].astype(str)
Result
To rename column
df.rename(columns={'col1':'column1'})
Result