Hi bblank,
I am sorry for the misunderstanding. To delete/edit the CNAME and SRV records you pointed out will cause unexpected error when you use Office 365 services, so that once you point the name server to Microsoft you won’t be able to delete/edit those records in DNS manage.
One way to achieve the requirement is you post the name server back to the domain register and add those require DNS records at that side, please see Add your domain to Office 365 but continue to manage your domain's DNS records.
However there are some limitations in Office 365 services when Microsoft doesn’t host your DNS. If you add your domain name to Office 365 without redirecting your name server records to Office 365, consider the following:
• SharePoint Online: If you want to host a public website by using SharePoint Online, you must use the default address http://domain.sharepoint.com. It isn’t possible to use a different domain for the public website.
• Domains troubleshooting tool: Because you didn’t configure your name server records to point to Office 365 name servers, the Office 365 domains troubleshooting wizard will always report that your name server records are incorrect. You can disregard this warning because you have manually created the DNS records for each of your services.
• DNS manager: Microsoft Office 365 for professionals and small businesses provides DNS management tools that you can use to add custom DNS records. However, if you create, or have already created, custom records by using this tool, because the name server records for your domain doesn’t point to Office 365, the custom records won’t work. You must create, or re-create, any custom records by using your current DNS hosting provider.
• Future Office 365 updates: When we add new services to Office 365, we won’t be able to automatically add the DNS records that are required to enable the services to work on your domain. To use the services, you must manually add the DNS records at your DNS hosting provider.
Thanks,
Kent Gu