Wiki Editting Page Modification

I installed wiki plug-in a few days ago.
When some users press 'edit' in an article which is created by wiki plug-in, the edit page shows lots of versions which indicate that there were lots of versions before the post was made.

I would like to delete these versions except for the last one which provide the space with WYSWIG editting tool.

Is it possible only to show that space?
If you do not understand what I mention, you can see my page to understand. Here is the URL.

The last one in the edit page is the only one that I want to show to everybody not to confuse how to edit.

Thank you for your support.