When connecting to Excel, it is important that you link to a worksheet rather than a named region. In the table selection drop-down menu you can recognize the worksheets by there name and a trailing $ sign. If you link to named regions, editing data, especially inserting new records, will be problematic.
In the database setup, you can specify whether you allow inserting, updating and/or deletion of records, so please, check your settings in the database setup. For Excel, deleting records is not supported, but editing should be.
If you are connecting to a CSV file rather than a real Excel file, only inserting is supported, not updating and/or deletion.
For any further questions, please, be more explicit about the error messages you see or what exactly happens when you try to edit the data.
Senior Software Engineer
"A reasonable man adapts himself to the world. The unreasonable man persists in trying to adapt the world to himself. All progress, therefore, depends on the unreasonable man." (Bernard Shaw)