I should have found this years ago.
Like most of you reading this I get bugged by vCenter presuming this is my first Rodeo, as they say.
Everytime you go to a new Datacentre/Cluster/Folder/VM* (Delete as appropriate) it gives me the Getting Started pages.
So today I found the off switches:
For C# Client
For the Web Client
Job done. You are now L33t @ vCenter