diff --git a/doc/source/drivers.rst b/doc/source/drivers.rst
index 57b8a4a..92616d1 100644
--- a/doc/source/drivers.rst
+++ b/doc/source/drivers.rst
@@ -467,12 +467,29 @@ following:
 
 * Remove your project from ``zuul/layout.yaml``.
 
-* Replace the contents of
-  ``gerrit/acls/openstack/<projectname>.config`` with::
+* By default, project ACLs are defined in a file called
+  ``gerrit/acls/openstack/<projectname>.config``. If this file exists,
+  replace the contents with::
 
     [project]
     state = read only
 
+* If a file called ``gerrit/acls/openstack/<projectname>.config`` does
+  not exist, that implies that your project shared ACLs with some other
+  project(s). You will need to do two things in that case:
+
+  #. Find the entry for your project in ``gerrit/projects.yaml`` and
+     delete the line which defines the acl-config. This will cause the
+     default to be used, and that default is a file that you create
+     next.
+
+  #. Create and submit a new file called
+     ``gerrit/acls/openstack/<projectname>.config`` which contains the
+     text::
+
+       [project]
+       state = read only
+
 * Remove your project from ``gerritbot/channels.yaml``.
 
 Remove Repository from the Governance Repository