I will like to make an enquiry on my PhD pursuit :I have a BSc in Economic and MSc in Human Resource Management but I am confused on the area to focus on for my PhD.is it possible I pursue a phd in Economics. Your candid advice and quick response will be appreciated. .
Thank you.

What interests you? What topics do you want research?

I would recommend to look at those questions and find a few areas you are interested in. Then decide what field to study in. You can absolutely do a PhD in either of those fields, I would just choose the area before department.

I think what Rewt is saying is that you need to think about what you want to do a PhD on - You can definitely do something on economics, but that is a huge field and you need to decide on a research idea on a very small part of it. Here's a website that lists 100 different topics so you can see what I mean:
https://www.ivoryresearch.com/library/dissertation-topics/economics-dissertation-topics/

Once you have a topic, the department rewt is referring to is where you can study it - You would have to find a department that does research in a related area or a supervisor with particular interests. It's a case of looking at what literature is already out there and who is writing it!