I am a new one to Magento, How to hide theme details like WordPress in Magento?
Actually, I usually use to hide WordPress with some plugins in the same case is there any plugin for Magento?
Although there is no specific plugin or module or service to do so in Magento, but you can rename theme folder name to whatever you want. It will hide actual theme name from front-end users.
Apart from that, when you merge CSS and JS from
System > Configuration > Advanced (Developer) > CSS Settings, Magento hides skin paths for JS and CSS files and combines these files into 1 file which is located into media folder.
In this way, you can hide path for CSS and JS files of theme, but still path for theme images can not be made hidden.
If you want to hide those also, you need to use CDN service to host images for theme.
I hope I was clear enough to explain what you asked.