Rocker arms can be removed without removing the cylinder bolts. But to do so, requires use of this tool:

https://rotunda.spx.com/en-US/Pages/...x?itemID=18452

This tool is used to to compress the valve springs by clamping down on the valve bridges, with the fuel injector removed.

If you do manage to obtain this tool, be very careful not to drop the rocker arm pivot ball during rocker arm removal. Removal by this method ensures that cylinder head to block clamping is not disturbed.