Tableau Online: How do I get rid of the automatically displayed 'Abc' column when adding a field to Rows?

I'm trying to put together an Excel style report on Tableau where the rows have an id and some aggregated fields.

Eg.

id | sum(revenue) | sum(hours)
1.       100.           10 
2.       200.           20
3        399.           40

However, whether I have just the ids or include the aggregated fields, there is an extra column. It has no header and displays 'Abc' in each row.

Eg.

id | sum( revenue) | sum(hours) |
1.       100.           10        'Abc'
2.       200.           20        'Abc'
3.       399.           40        'Abc'

What is this extra column and is there any way to hide it? Thank you.

Screenshot:

You can drag your measure into the text shelf and Ref Id to Rows. This will give you a text table.

Or you can drag your measure to Columns for a chart.

If you need to just show your Ref Id with no measure, you can hover over the far-right edge of the Abc area and when the double arrow icon shows, you can drag text area to the left to hide it.