我想要删掉有负值的行

为什么总是报错呢？
TypeError: list indices must be integers or slices, not str
```python
import pandas as pd
import openpyxl
from openpyxl import load_workbook
df = load_workbook('A.xlsx')
ws1=['SC']

for i in ws1['2021']:
    if i < 0:
        df = df.drop(df.index(i), axis=0)

df.to_excel('df_new.xlsx')

```

筛除负值不是直接df[df['column']>=0]就行么