Sorry that you are seeing this issue. I assume you are working with MyEclipse 10.x.
1. How did you install MyEclipse 10.x ? Did you install MyEclipse on top of Eclipse using the archived update site for MyEclipse 10.x?
2. In MyEclipse, you can run the uninstall program that is installed with MyEclipse (check the Uninstaller folder in the MyEclipse installation dir) or you can remove the installation manually.
Please check this FAQ for manual uninstall of MyEclipse : https://www.genuitec.com/forums/topic/installation-how-to-manually-uninstall-myeclipse/
Versions earlier than MyEclipse 2014 are no longer fully supported. So I suggest you install MyEclipse 2015 or the newest release MyEclipse 2016 CI, which is based on Eclipse Mars. Your current license is valid for newer releases of MyEclipse as well.