1. From your Podcast Dashboard, go to the "Publish"->"Episodes".

 

2. Create a new episode or click the pencil icon of an already published/drafted episode. 

 

3. Then click the "More Episode Settings" button at the bottom of the edit box. 

  

 

4. Edit the permalink as you like in the “Permalink” field. Please note that only alphanumeric characters or dash and underline are allowed.