diff --git a/cps/admin.py b/cps/admin.py
index 29f5fb20..706dce39 100644
--- a/cps/admin.py
+++ b/cps/admin.py
@@ -1415,7 +1415,16 @@ def _delete_user(content):
             for us in ub.session.query(ub.Shelf).filter(content.id == ub.Shelf.user_id):
                 ub.session.query(ub.BookShelf).filter(us.id == ub.BookShelf.shelf).delete()
             ub.session.query(ub.Shelf).filter(content.id == ub.Shelf.user_id).delete()
+            ub.session.query(ub.Bookmark).filter(content.id == ub.Bookmark.user_id).delete()
             ub.session.query(ub.User).filter(ub.User.id == content.id).delete()
+            ub.session.query(ub.ArchivedBook).filter(ub.ArchivedBook.user_id == content.id).delete()
+            ub.session.query(ub.RemoteAuthToken).filter(ub.RemoteAuthToken.user_id == content.id).delete()
+            ub.session.query(ub.User_Sessions).filter(ub.User_Sessions.user_id == content.id).delete()
+            ub.session.query(ub.KoboSyncedBooks).filter(ub.KoboSyncedBooks.user_id == content.id).delete()
+            # delete KoboReadingState and all it's children
+            kobo_entries = ub.session.query(ub.KoboReadingState).filter(ub.KoboReadingState.user_id == content.id).all()
+            for kobo_entry in kobo_entries:
+                ub.session.delete(kobo_entry)
             ub.session_commit()
             log.info(u"User {} deleted".format(content.name))
             return(_(u"User '%(nick)s' deleted", nick=content.name))
diff --git a/cps/kobo.py b/cps/kobo.py
index 706056d3..67304c93 100644
--- a/cps/kobo.py
+++ b/cps/kobo.py
@@ -297,7 +297,8 @@ def HandleSyncRequest():
 
     changed_reading_states = changed_reading_states.filter(
         and_(ub.KoboReadingState.user_id == current_user.id,
-             ub.KoboReadingState.book_id.notin_(reading_states_in_new_entitlements)))
+             ub.KoboReadingState.book_id.notin_(reading_states_in_new_entitlements)))\
+        .order_by(ub.KoboReadingState.last_modified)
     cont_sync |= bool(changed_reading_states.count() > SYNC_ITEM_LIMIT)
     for kobo_reading_state in changed_reading_states.limit(SYNC_ITEM_LIMIT).all():
         book = calibre_db.session.query(db.Books).filter(db.Books.id == kobo_reading_state.book_id).one_or_none()
@@ -849,7 +850,7 @@ def get_ub_read_status(kobo_read_status):
 
 def get_or_create_reading_state(book_id):
     book_read = ub.session.query(ub.ReadBook).filter(ub.ReadBook.book_id == book_id,
-                                                          ub.ReadBook.user_id == current_user.id).one_or_none()
+                                                          ub.ReadBook.user_id == int(current_user.id)).one_or_none()
     if not book_read:
         book_read = ub.ReadBook(user_id=current_user.id, book_id=book_id)
     if not book_read.kobo_reading_state:
diff --git a/cps/kobo_sync_status.py b/cps/kobo_sync_status.py
index a22ec165..6df0a503 100644
--- a/cps/kobo_sync_status.py
+++ b/cps/kobo_sync_status.py
@@ -60,7 +60,7 @@ def change_archived_books(book_id, state=None, message=None):
     return archived_book.is_archived
 
 
-# select all books which are synced by the current user and do not belong to a synced shelf and them to archive
+# select all books which are synced by the current user and do not belong to a synced shelf and set them to archive
 # select all shelves from current user which are synced and do not belong to the "only sync" shelves
 def update_on_sync_shelfs(user_id):
     books_to_archive = (ub.session.query(ub.KoboSyncedBooks)
@@ -75,6 +75,7 @@ def update_on_sync_shelfs(user_id):
             .filter(ub.KoboSyncedBooks.user_id == user_id).delete()
         ub.session_commit()
 
+    # Search all shelf which are currently not synced
     shelves_to_archive = ub.session.query(ub.Shelf).filter(ub.Shelf.user_id == user_id).filter(
         ub.Shelf.kobo_sync == 0).all()
     for a in shelves_to_archive:
diff --git a/cps/shelf.py b/cps/shelf.py
index b1fbdd04..29a4fe99 100644
--- a/cps/shelf.py
+++ b/cps/shelf.py
@@ -251,6 +251,10 @@ def create_edit_shelf(shelf, page_title, page, shelf_id=False):
         is_public = 1 if to_save.get("is_public") else 0
         if config.config_kobo_sync:
             shelf.kobo_sync = True if to_save.get("kobo_sync") else False
+            if shelf.kobo_sync:
+                ub.session.query(ub.ShelfArchive).filter(ub.ShelfArchive.user_id == current_user.id).filter(
+                    ub.ShelfArchive.uuid == shelf.uuid).delete()
+                ub.session_commit()
         shelf_title = to_save.get("title", "")
         if check_shelf_is_unique(shelf, shelf_title, is_public, shelf_id):
             shelf.name = shelf_title
diff --git a/cps/ub.py b/cps/ub.py
index 6b3c27ca..1d5db58a 100644
--- a/cps/ub.py
+++ b/cps/ub.py
@@ -421,8 +421,8 @@ class KoboReadingState(Base):
     book_id = Column(Integer)
     last_modified = Column(DateTime, default=datetime.datetime.utcnow, onupdate=datetime.datetime.utcnow)
     priority_timestamp = Column(DateTime, default=datetime.datetime.utcnow, onupdate=datetime.datetime.utcnow)
-    current_bookmark = relationship("KoboBookmark", uselist=False, backref="kobo_reading_state", cascade="all")
-    statistics = relationship("KoboStatistics", uselist=False, backref="kobo_reading_state", cascade="all")
+    current_bookmark = relationship("KoboBookmark", uselist=False, backref="kobo_reading_state", cascade="all, delete")
+    statistics = relationship("KoboStatistics", uselist=False, backref="kobo_reading_state", cascade="all, delete")
 
 
 class KoboBookmark(Base):