Deleting all Webform Submissions and Content from specific IP
You could use Views Bulk Operations.

Add Bulk operations: Content as a field and check mark Delete item under Selected Bulk Operations. Make your view format as Table.

You could try using IP Address manager or User IP Log and hopefully one of these modules will allow you to add IP address as a field to your view.

In your View, under Advanced, you may possibly need to add a relationship of author to your view so you can access user fields (IP Field).