If you've selected a template from our Template Gallery you'll likely want to delete the sample records in the template.
Step 1: select all rows in a table
Quickly select all rows in a table by clicking the checkbox on the left side of the table's header row.
Step 2: delete records
Once you've selected the records you want to delete, right-click on any row in the selection and click "Delete all selected records". Then select "Delete" again to confirm.
For more on deleting records, please see the support article titled "Delete Records."