Failure to update database

[Tom Rust]

I've downloaded and run the add-on, and I can connect and edit a table from the database. But when I try to clear the contents of a set of rows, then commit the change back to the database, the field comes back orange and I get
The server returned 6 warning(s):
1: Query did not match any rows in the DB, values in the row 2 may have changed; please refresh values from the DB.
2: Query did not match any rows in the DB, values in the row 3 may have changed; please refresh values from the DB.
3: Query did not match any rows in the DB, values in the row 4 may have changed; please refresh values from the DB.
4: Query did not match any rows in the DB, values in the row 5 may have changed; please refresh values from the DB.

I need to delete the data filled in the tables and reset the database. Is there another way I can fix this?
Thanks!