RE: Remove or Hide out of the box Account/Contact/Opportunity Creation popup window upon Lead Qualification
                     
                    
                      
                        Hi Eric,
In the Sales Hub, at the bottom of the site map, select Change area 
 and then select App Settings.
Then in site map, select Overview, and on the Overview page, select Manage for Auto-create records for newly qualified leads.

Select Yes and Save. 

The pop-up window will no longer appear. However, in this case, when the user qualifies a Lead, it will create an Account, a Contact and an Opportunity automatically.