There are several ways to approach this. 

If you want to delete the data outside of a workflow at design time, you could just use SQL Management Studio and go to the K2 SmartBox database table that holds your data and delete all the rows.  You could also download a tool like K2 Commander from blackmarket to do this.  http://www.k2underground.com/k2/ProjectHome.aspx?ProjectID=39

If you want to delete the data at runtime, you could use the SmartObject event in an iteration similar to this post:

http://www.k2underground.com/forums/post/25500.aspx

---

The statements and opinions made in my postings are my own, and do not reflect the opinions of SourceCode Technology Holdings, Inc. or its subsidiaries. All information is provided as is with no warranties, express or implied, and grants no rights or licenses.