diff --git a/iceland/core/src/main/java/org/n52/iceland/config/json/JsonAdminUserDao.java b/iceland/core/src/main/java/org/n52/iceland/config/json/JsonAdminUserDao.java
index efdecfa2d..b9bfff2c3 100644
--- a/iceland/core/src/main/java/org/n52/iceland/config/json/JsonAdminUserDao.java
+++ b/iceland/core/src/main/java/org/n52/iceland/config/json/JsonAdminUserDao.java
@@ -97,8 +97,13 @@ public void saveAdminUser(AdministratorUser user) {
 
     @Override
     public void deleteAll() {
-        this.configuration().delete();
+        configuration().writeLock().lock();
+        try {
+            getConfiguration().remove(JsonConstants.USERS);
+            configuration().scheduleWrite();
+        } finally {
+            configuration().writeLock().unlock();
+        }
     }
 
-
 }