Hey @syefulislam, thank you for your interest in ownCloud!
Check this old answer on central on this topic: https://central.owncloud.org/t/predefine-server-address/4612/2 - of course, you can easily go ahead and modify the source code by yourself!
If you need further branding options you could try ownBrander (part of the OC Enterprise Ed. perks) to do so, it's way more comprehensive than modifying the code and abstracts all that work for you 