Improve guide for dealing with spam on pagure

Add `pagure-admin sanitize-spam-user` as another step to guide.

Signed-off-by: Michal Konecny <mkonecny@redhat.com>

modules/howtos/pages/pagure_spam.adoc

@@ -21,6 +21,31 @@ For example:
 pagure-admin block-user spamuser 2060-01-01
 ----
 
+== Remove all the content created by the spam user
+
+Still on pagure02.fedoraproject.org. As root user run the following command:
+
+----
+pagure-admin sanitize-spam-user <spamer_username> <your_username>
+----
+
+For example:
+
+----
+pagure-admin sanitize-spam-user spamuser admin
+----
+
+== Unwatch the projects watched by the user
+
+If the spam is persistent even after blocking the user on the project you should
+remove the user from watchlist for the project.
+
+----
+pagure-admin update-watch namespace/project <username> -s 0
+----
+
+NOTE: For now it's not easy to find all the projects the user is watching.
+
 == Disable user in IPA
 
 === Frontend