Click on the Navigation widget's Edit button and make sure that Group pages redirect to the first subpage is not checked and save - refer to this image. This should disable redirection for the group page in your menu.Greetings,
You have been given and answer in a support ticket. I will paste the response here for your reference:
You can use a redirect page instead of a group page. In order to do that click on your Group page and in the Title & properties editor choose This page redirects to another page and click on Set page to redirect to button. Select Web Address radio button and in the URL field type ~/#. Now this Redirect page will redirect to 'nowhere' and you can use it as a group page. I have recorded a short video for your convenience.
I hope this helps and please let me know if you require any further assistance.
the Telerik team
Please let us know if the provided solution works for you.All the best,