Thanks for your question. If you pull down the Help menu in the upper right corner of the Media/Assistant admin submenu and click the “Bulk Actions” tab you will get some help on Bulk Edit operations. For your application, have a look at:
You can update the Title, Caption, Description and ALT Text values for all of the selected attachments. You can use a Content Template to customize the values based on attachment-specific data sources. You can also delete the content of a field by entering the special template:[+empty+]
value.
I am marking this topic resolved, but please update it if you have problems or further questions regarding the above solution. Thanks for your interest in the plugin.