diff --git a/ml4/2_5_1_Exercise.ipynb b/ml4/2_5_1_Exercise.ipynb
index 3d1f1c0..37f40f6 100644
--- a/ml4/2_5_1_Exercise.ipynb
+++ b/ml4/2_5_1_Exercise.ipynb
@@ -211,15 +211,6 @@
     "You can also use the library [sklearn-genetic-opt](https://sklearn-genetic-opt.readthedocs.io/en/stable/index.html)"
    ]
   },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "# Optional exercises\n",
-    "\n",
-    "Here there is a proposed optional exercise."
-   ]
-  },
   {
    "cell_type": "markdown",
    "metadata": {},