How to change permissions for creating articles and blogs for Vbulletin 5.1?

Change the permissions for creating articles:
In the Admin CP of your vbulletin based system where you set permissions for all channels. Go to Channel Management -> Channel Permissions. Scroll to the Articles channel. Edit your usergroups and remove the “Can Post Topic” permission. All sub-channels will inherit those permissions.

Change the permissions for creating blogs:
will add this later.