why need to remove assertions before Adding Xpath match(which is put before request step)

Abit of confusing.

1. Why asserton step without even calling the request?

2. Can't be using predefined assertion which is part of requestion step (without the existing step)?

If you have expected values varies for each row, then use custom propeties to have the row data saved and assert each test against custom property. This way, predefined assertion can be used instead of adding and removing each time.