Step 1. Deactivate the Extension
1.1. If you have SSH access to the server, run the following command:
php bin/magento module:disable GoMage_LightCheckout
1.2. If you do not have SSH access, log in to the admin panel, go to Stores > Configuration > Advanced > Advanced, choose GoMage_LightCheckout and set the value to Disable. Then save the changes.
The extension is now deactivated.
Step 2. Delete Folder
BE VERY CAREFUL WHEN DELETING FILES OR FOLDERS, YOU MAY ACCIDENTALLY DELETE WRONG FILES OR FOLDERS.
Using an FTP client, delete the following folder:
<your Magento® install dir>/app/code/GoMage/LightCheckout
Step 3. Edit the Config file
Find your <your Magento® install dir>/app/etc/config.php file and open it in a text editor.
Find the following line: 'GoMage_LightCheckout' => 1 and delete it.
Step 4. Delete Data from the Database
Run the following script on your server (MySQL) to delete data from the database:
delete from core_config_data where path like 'gomage_light_checkout_configuration%';
drop table gomage_postcode;
drop table gomage_social_customer;
delete from setup_module where module = 'GoMage_LightCheckout';
Step 5. Clear Cache
Go to System → Cache Management and clear the store cache.