Using purchased themes to make and resell different software

Can I purchase a HTML theme from Envato then modify it to fit WordPress or Opencart or Joomla theme or modify it to work with any opensource projects and resell?
Kindly advice

No - items cannot be resold ‘as is’ and you need permission from the original author to convert and resell the design.

Even then - items cannot be used as part of on-demand or other software - each license (purchase) is for one project/website