bug ! generating white screen on edit/post/new

hi

Big, serious problem.

Found the culprit of my white screen of death : Infinite SEO

also have a blank screen on http://mysite.com/wp-admin/network/settings.php?page=wds_wizard

Problem, ISEO set many entries in the tables , and does NOT delete properly in case of deactivation.

How to totally clean the database and reinstall it ?