How do I delete a sub-set of records from a connected table?

I have a large number of records that I've imported into a table over a long period of time via the connected tables option (with the add, update, but do not remove option set) and now no longer need to reference some of the older data that was imported. I'd like to delete these older records in order to avoid issues with running out of space, but it seems I'm unable to do so.

I've checked that I'm in an Administrator role and that I have the green checkmark next to 'delete' for the table I'm looking at. 

What I tried to do was to filter only the items I wanted to delete in a report, click grid edit, highlight the row, right click and select "delete record". When I do this though, I get an error message that says "You do not have permission to delete items".

This was the guide I followed:
http://help.quickbase.com/user-assistance/deleting_multiple_records.html

Is there anything else I need to enable as  permission on my role to delete accounts? Could the use of a connected table be not allowing me to remove records for some reason?

BONUS QUESTION: Assuming I can somehow delete records, is there a more efficient way to delete multiple records can highlighting multiple rows via grid edit? I have ~10k records that I'd like to remove...