Programmatically remove content from a group In order to add a node to any group in Drupal 8, I use the following code.

$group-&gt;addContent($node, 'group_node:article');


Now, for removing content from a group, I have tried $group-&gt;removeContent($node, 'group_node:article'); and $group-&gt;removeContent($node); without success. All I obtained is the following error message.


  Error: Call to undefined method Drupal\group\Entity\Group::removeContent() in Drupal\my_valetop_extras\Plugin\WebformHandler\CustomWebformHandler->submitForm()


Finally, I have managed to remove content from a group using this code.

$type = 'group_node:' . $node-&gt;getType();
$current_node = $group-&gt;getContent($type, ['entity_id' =&gt; $node_id]);
$content = array_values($current_node)[0];
$content-&gt;delete();


But  believe I can remove a single node from a group with a simple line of code.

How can I achieve it?
I believe that function was overlooked by the developers. In the issues queue for the Group module, which is what your error message refers to, I can see that the inverse of addMember(), removeMember(), was added later in the project's life. It seems reasonable to suppose that the inverse of addContent() was also overlooked, with the only difference being that it has remained unimplemented to this day.

There are no functions with names hinting at content-removing behaviour evident in the module's GroupInterface definition, so I recommend opening a new issue with the project to let them know about the gap.