Users cannot use the backspace in the Text Area control to clear the text entered.
If you have added a 'Text Area control' to a read-only table, and making it editable in your rules, you will not be able to use the backspace when clearing data.
You will only be able to clear text by highlighting the text and pressing Delete key.
To resolve this:
Clear the Read-Only checkbox of the table control in layout tab.
Make the table Editable in 'Specify edit state for View controls' action.