1. Log into the CRM Webserver where CRM is installed
  2. Using Windows Explorer goto C:\Program Files\Microsoft CRM Server\CRMWeb\Tools\FormEditor
  3. Edit the file formeditor.aspx
  4. Find the JavaScript variable “_iMaxTabs”.  It is by default set to 8.
  5. Change the value to your desired limitation
  6. Save and close the file
  7. Open a cmd prompt
  8. Type IISReset to reset the iis website