How to remove top.arama

How do I remove this browser from my pc?

Hello Mike.
I request you to be more specific about the issue that you face to assist you further.
Thank you.

Hello Mike.
I request you to be more specific about the issue that you face to assist you further.
Thank you.

When I start Firefox on one of my PCs instead of going to the previously set home pages, Firefox opens a search page called Top.Arama.com.  I have looked for details on the internet and it is described as a browser hijacker which should be removed, but I can't wwork out how to do this.