Can I use Intel Galileo board without any OS installed in it? My intention is to use the Galileo board like an "Arduino Uno" board. I know that Arduino Uno uses a microcontroller and Galileo has a processor in it. But I would like to know with writing some C language program (like a firmware probably with some IDE) and if I can load that to the Galileo and control some devices like LEDs or motors. If yes please let me know how/provide some URLs where it mentioned about some toy projects without an OS on a Galileo.
Things aren't quite as bleak as some of the other commentors are making them out.
The short answer is yes, but with alot of caveats. Writing bare metal for Galileo is a bit complex due to x86 being a somewhat complicate architecture and the SoC in Galileo isnt as straight forward as a simple STM32 or ESP32 or something like that. If you are looking for more information (all the information) on the hardware, you can find that here: https://www.intel.com/content/dam/support/us/en/documents/processors/quark/sb/329678_intelquarkcore_hwrefman_002.pdf
However, starting from that low level is probably not ideal unless you are trying to learn/want to learn how to write an OS/firmware. Its a great exercise but takes lot of effort and knowledge to get working. And in reality, for what you describe, it sounds like you want to control the system from a higher-level, but not ontop of something as complex and latency insensitive like linux. This is were you might want to take a look at a Realtime Operating System (RTOS); and there is an open source, permissive-licensed RTOS that claims to work on Galileo, Zephyr RTOS: https://www.zephyrproject.org/
Based on what you are requesting, I would work ontop of Zephyr instead of trying to reinvent the wheel and run on Galileo bare metal. If you still want to pursue that lower level, at least you can refer to the documentation on Zephyr's supported board page as well as its own source code to build up a program for the Quark X1000 on Galileo.