title: Memory usage is close to the limit in Google Colab
body: <p>I'm using Google Colab to train my model. After training, I want to change the model but I can't because there is not enough RAM for it. I tried to re-assign old model to <code>None</code> but RAM used didn't decrease.</p>
  
  <p><a href="https://i.stack.imgur.com/QLKfx.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QLKfx.png" alt="enter image description here"></a></p>
  
  <p>I don't want to close the session and start from the beginning. Is there any way to free up RAM used in google colab?</p>