As you have chosen to be anonymous, it is not possible to find out your background. As you are teaching MBAs, I am sure that you have done a Masters degree. Did you study Research Methodology as a subject? If so, you should know how to go about selecting a topic. I found some ideas for topic at
https://dissertationsage.co.uk/disse...ce-management/
Kindly drop me a Private Message giving more details about your qualifications and where you would like to do your PhD and in what mode, etc.