You can manage the installed plugins in the Plugin Manager dialog. You can find it in the ReadyAPI toolbar:
You cannot remove the Git-related UI elements in 2.6.0. It isn't a plugin anymore.
If you need to make your project to be non-composite again you can just set the property "Composite Project" to "false" in "Project Properties".
Thanks for your help, Alexander!
@tsuarezc, is this what you were looking for? If this reply doesn't answer your question, could you please clarify your request? Why do you want to disable the integration? Had you activated it before? Did you face any issues?