reset_index pandas

df.reset_index(drop=True, inplace=True)

>>> s.reset_index(inplace=True, drop=True)
>>> s
0    1
1    2
2    3
3    4
Name: foo, dtype: int64

df.reset_index(drop=True)

In [194]: df.reset_index(drop=True)
Out[194]: 
  _worker_id  foo
0          A    1
1          B    2
2          C    3