How to remove levels from a multi-indexed dataframe?

df.reset_index(level=2, drop=True)
Out[29]: 
     A
1 1  8
  3  9

You don't need to create a new DataFrame instance! You can modify the index:

df.index = df.index.droplevel(2)
df

     A
1 1  8
  3  9

You can also specify negative indices, for selection from the end:

df.index = df.index.droplevel(-1)