If you want no one to be able to access your website for a temporary period you can put your site in either coming soon or maintenance mode. To do this go to > Settings > Coming Soon pro and either enable coming soon or Maintenance mode and then save the changes.
If you are wanting to put your website offline for only a short period of time we recommend using Maintenance mode as this will not influence your google rankings or pages that are indexed. If however you are planning on keeping your website not visible for a long period of time then choose coming soon mode
When you want to make your website live go to > Settings > Coming Soon pro and choose the disable option and save the changes