How to disable your PrestaShop store
If you need to deactivate your PrestaShop temporarily, you can do it from the backend of your store. It's something that's good to be done when performing some maintenance task like updating, for example.
To disable your store, log in to the admin panel, then click on the Preferences tab. There, on the general page of the Preferences tab, you'll see that the first option is Enable Shop. Mark the No button for that option to disable the store. Then in the field for the next option (Maintenance IP addresses) type your IP address.
If you don't know what your IP is, you can learn it from whatismyip.org, or just click on the Add my IP address button that's next to the field. If you want to, you can also list other IP addresses. If you don't put your IP address in the field for Maintenance IP addresses, you won't be able to access the frontend of your store. You'll still be able to access the backend though, so you'll be able to fix that, and there's no danger of locking yourself out of the admin panel. All other IP addresses, except for the listed ones, won't be able to access the store.
After you change these options don't forget to click on the Save button at the bottom of the page to disable the shop.