Remove unwanted rows

Hi,

I have created a sample data in which column Id has values like underscore (_), (null), (blank) etc. (refer rows 5 to 8 in attached file).

I understand there is an option "Remove Empty" which removes blank rows. In this case, row no. 5 will be removed. To remove the other unwanted rows, I will have to replace each of those values with a blank row and then use above option.

But when I select the column Id and navigate to Remove Rows -> Remove Blank Rows, none of the rows are removed.

How does the Remove Blank Rows option work?

Please explain using this same example and sample data. 

Thanks,

Vishy