Hi Robert, 

The process action Close document is not a valid starting point for a Process flow. We will update the Documentation accordingly so I don't have to give you the bad news.

Hi Mark,

Thanks Documentation for the bad news! 

Can this be achieved in a different way instead of a process flow?

It depends a bit on what you want to achieve. What should the Task do? And what actions happened before the user decides to close the screen? If I know that, I can probably find a way to achieve the desired goal.

When exiting the screen for any reason, data should be deleted using the username (tsf_user ()) across multiple tables. This so that the data on the database is deleted and when the screen is opened next time it is empty for use.

Could you do it the other way like upon Opening the document/screen cleaning the data that is present?

For now I am going to apply it this way, however this is not the way I intended. Thanks.

For all process flow actions, we added whether they can be used as a starting point and/or as a system flow https://docs.thinkwisesoftware.com/docs/sf/process_flows.html#available-process-actions
For example:

Activate document