A simple customization that I would do for clients was remove some of the system views that come out of the box but aren't used. You used to be able to accomplish this by creating a team and then sharing a Public View with that team. Sharing of System Views is no longer available. You can have this functionality with views created in Advanced Find, just share the view with a team or individual users. But not the System Views.
The only ways that I've seen to get around this are to either modify the EntityXML or update SQL. Either way you update the IsPrivate attribute from 0 to 1. If you do this in the EntityXML you will make the change and then upload the XML. If you do it through the database then the change will occur as soon as you update the database...or so I'm told. Please remember that UPDATES to the CRM databases are NOT SUPPORTED. If you go this route you are on your own and Microsoft will wipe their hands clean of you and your system. So, please, do yourself a favor and backup your databases before you attempt anything like this, and do this in a development environment first, not on a live server!
Here's the SQL script that I've used:
set IsPrivate = 1
where SavedQueryId = '00000000-0000-0000-00AA-000010001002'
--replace the SavedQueryId with the ID of the SavedQuery to be hidden
Once you make this change the views will drop from site completely. Meaning you won't even see them in the Customizations of the Entity area. That's because they've been marked as being private but no rights were given to anyone to be able to see that private view so it completely "disappears."
If anyone else has any other solution for this issue, I'd love to hear it. Typically I have clients who don't want to see the "Accounts with no Orders in the Last 6 months" and creating new views is not a problem.
Good luck out there!
Dynamic Methods Inc.