Deleting a cell removes the entire row in Numbers

When I add rows to my numbers table it copies information from the cells above. If I try and erase the contents in any of these cells it just deletes the row. These are tables that have been filtered down from a bigger table.

How do I erase contents without deleting the row or how do I add rows without copying content from the cells above.

Essentially I want to add blank rows to which I can apply new formulas and/or data.

[Re-Titled by Moderator]