pandas delete all rows in dataframe if in another dataframe code example

Example 1: remove rows from a dataframe that are present in another dataframe?

df.loc[~((df.Product_Num.isin(df2['Product_Num']))&(df.Price.isin(df2['Price']))),:]
Out[246]: 
    Product_Num     Date  Description  Price
0            10   1-1-18  FruitSnacks   2.99
1            10   1-2-18  FruitSnacks   2.99
4            10  1-10-18  FruitSnacks   2.99
5            45   1-1-18       Apples   2.99
6            45   1-3-18       Apples   2.99
7            45   1-5-18       Apples   2.99
11           45  1-15-18       Apples   2.99

Example 2: delete rows in a table that are present in another table pandas

print (pd.merge(a,b, indicator=True, how='outer')
         .query('_merge=="left_only"')
         .drop('_merge', axis=1))
   0   1
0  1  10
2  3  30