Hi Rose,
1. For the custom filter widget, there isn't any setting available to remove it. If you really want to remove it, you can perform a template override on this file:
JoomlaFolder/components/com_easysocial/themes/wireframe/dashboard/default/default.php
Duplicate the file and place it here(create directory if it does not exist):
templates/yourCurrentTemplate/dashboard/default/default.php
Then, in the duplicate file, remove this block of code which is responsible for displaying the custom filter widget and save the changes:
http://take.ms/HFCgV
2. Actually what is the issue with the mobile layout? Can you provide some screenshots so I can better understand the issue? Thanks. I also tested your site on my mobile device and the layout seems fine.