The release notes for Photoshop CS6 Extension Manager say to uninstall Photoshop CS6 Extension Manager on Mac, go to Utilities -> Adobe Installers and double-click Adobe Extension Manager CS6. But there is no Adobe Extension Manager CS6 under Adobe Installers, only Uninstall Adobe Photoshop CS6.
So, how do I do it?
EM CS6 can be uninstalled only if all its supported products are uninstalled. If it is useless for you and you want to save disk space, you can simply delete its folder.