[Python] Pandas Key Error in dropna call for specific subsets

I am trying to drop all columns that have specific rows (in a range by index) all empty. For example, in the following example table,

colA colB colC colD
rowA val val val val
rowB val val val
rowC val val
rowD val


I wish to drop all columns with just rowC to row D all empty, meaning drop colB and colD. Following is the line of code that I have currently:

df = df.dropna(subset=df.iloc[2:], axis=1, how="all")


I was attempting to use dropna using a subset of rows 3~. However, when I run the code the following KeyError occurs:

File "/Users/zia/Desktop/work/Automation/test.py", line 78, in CONVPVT
df = df.dropna(subset=df.iloc[2:45], axis=1, how="all")
File "/Users/zia/opt/anaconda3/lib/python3.9/site-packages/pandas/util/_decorators.py", line 311, in wrapper
return func(*args, **kwargs)
File "/Users/zia/opt/anaconda3/lib/python3.9/site-packages/pandas/core/frame.py", line 6002, in dropna
raise KeyError(np.array(subset)[check].tolist())


How can I fix this?

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