Hi Omar, 

if the website is currently online, you can simply delete the relative files from the server destination folder. Here you can find a guide about this subject: https://guide.websitex5.com/en/support/solutions/articles/44000807700

Thanks! Kind regards.

I like to put up an"Under Construction" page.  You can modify your htaccess file and add

DirectoryIndex filename.html

to redirect your initial page to the temporary file.  Then remove that line after you are done to send users back to your index.html page.