The delete button gives you the option to clear or delete your decision logic, as well as delete rows and/or columns.
Navigate to the "Cell" panel and click on the Delete button drop-down to be presented with the action you want to do.
From here you can select to:
Clear Logic: will clear the decision logic of all elements and format.
Delete Logic: will delete the whole decision logic and its page.
Delete Row: will delete the selected row.
Delete Column: will delete the selected column.