How to hide a contact's add rows in a company?

By default, a company's contact list and a contact's company list have a blank line to link a new element directly.

To automatically hide the line adding a contact in a company, go to the CRM Admin (top menu -> CRM Admin), then click on the tab "13. Settings".

Uncheck the "Automatically display an add line" box, then click the Save button.

A company's contact list and a contact's company list no longer display a blank line.
To display a blank line, click on the button "Add a link to a contact".

A blank line appears.