The answer to your first question is yes. It is possible to remove Ubuntu and keep grub.
For your second - it is usually helpful to stick with the loader that comes with the OS.
- while you are still playing around with different OSs - finding the one that is right for you - you are usually well advised to multi-boot instead. Keep the grub/ubuntu install as is - the OS installer will usually have partition-management tools included: use those to resize Ubuntu's partition. Install the OS bootloader to someplace other than MBR - then use the chainload entry in grub as per the wiki you linked to.
The point of this is that different Oss will want to automatically manage the system - which will include editing the bootloader configuration file when there is a kernel update. This approach gives each OS it's own bootloader to fiddle about with, avoiding conflicts and confusion.