lavinya on "[Plugin: WordPress SEO by Yoast] How to disable this plugin wp-signup wp-login, wp-activate pages"

Hello i'm using wp 3.5.1 multisite. and activate yoast seo 1.4.1.

How to disable this yoast seo plugin wp-signup.php wp-login.php, wp-activate pages?

This plugin; BECAUSE it does not work correctly on these pages..
(title missing, canonical url wrong .... etc)
please test my website http://weblogtr.com/wp-signup.php

Thanks.