You can apply for a master's degree, but you can't apply for a better school or get a scholarship without a diploma and a degree certificate.

A bachelor's degree and a letter of recommendation are usually necessary for an application. Your experience is more likely to succeed in applying for MBA or EMBA. After all, it is difficult for you to continue to make achievements in the academic field after you have left school for many years. Moreover, with your good practical experience, the business application is easy to succeed.