Maven plugin is not working perfectly,so I want to re-install in my eclipse. How do I remove Maven from eclipse?

When I am uninstalling 2 types but getting problems

1) eclipse market place--> Maven integration for eclipse luna(1.5.0) getting msg

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"m2e-wtp - Maven Integration for WTP" cannot be fully uninstalled because other installed software requires it.  The parts that are not required will be uninstalled.

and

2) Help > about eclipse > installation details > installed software

Under Eclipse ide for j2ee devlopers

There are 6 m2e avilable, but uninstall button is not enabled.

So how can I remove and re-install correctly? Thanks.