title: Removing rows with same foreign key but with different values
body: <p>I have a table with similar structure to the following:</p>
  
  <p><a href="https://i.stack.imgur.com/CSYds.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/CSYds.png" alt="enter image description here"></a></p>
  
  <p>I am looking for a way to remove all rows where role_id = 4, in cases where there is already a row with the same context_id and user_id and where the role_id = 3.</p>
  
  <p>for example this row should be removed:
  <a href="https://i.stack.imgur.com/OStNO.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/OStNO.png" alt="enter image description here"></a></p>
  
  <p>Since there is already a row with the same context_id, user_id and where the role_id = 3</p>