Microsoft released a very helpful article on how you can remove connectors from SCOM 2007 R2. Actually to do that they provided a PowerShell script. The knowledge base article is located here.
By default not all Service Manager connectors have scheduling option. For example SCOM connector has and AD connector doesn’t but that is only because the UI doesn’t provides it. Stefan Koell wrote a great article on how to schedule the AD connector or any other connector that does not have UI Schedule option. Without explaining more just read the article below.