Dropping rows from a PANDAS dataframe where some of the columns have value 0
I think you need create boolean DataFrame by compare all filtered columns values by scalar for not equality and then check all Trues per rows by all:

df = df[(df[['A','C']] != 0).all(axis=1)]
print (df)
   A  B  C
0  1  2  5
2  6  8  4


Details:

print (df[['A','C']] != 0)
       A      C
0   True   True
1   True  False
2   True   True
3  False   True

print ((df[['A','C']] != 0).all(axis=1))

0     True
1    False
2     True
3    False
dtype: bool


I think you need create boolean DataFrame by compare all values by scalar and then check any Trues per rows by any and last invert mask by ~:

df = df[~(df[['A','C']] == 0).any(axis=1)]


Details:

print (df[['A','C']])
   A  C
0  1  5
1  4  0
2  6  4
3  0  2

print (df[['A','C']] == 0)
       A      C
0  False  False
1  False   True
2  False  False
3   True  False

print ((df[['A','C']] == 0).any(axis=1))
0    False
1     True
2    False
3     True
dtype: bool

print (~(df[['A','C']] == 0).any(axis=1))
0     True
1    False
2     True
3    False
dtype: bool