Can i take a website offline through Cpanel in my website or there is another way, i need an experience that will tell users who visit the site at that moment that "This website is under maintainance try again later" while i am updating codes on the site.. pls how do i add this feature??

You can simply backup ur original index page then create another index page containing only that message you wish to be displayed to visitors. Replace the original index page with the new one.

LoremIpsum:
You can simply backup ur original index page then create another index page containing only that message you wish to be displayed to visitors. Replace the original index page with the new one.

Above is the best way to take it down.

Here is my take. Why take it down when you can grap all your files from cPanel, display a message in your index that "your site is under maintenance and user may experience some lags", while they continue interacting with your site. After editing you upload your new files to the server again.

SIDE NOTE:
taking it down completely may make you lose visitors and personally, it is not really a good idea.