Please follow the instructions precisely in order to disable the extension on your server successfully.
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, login 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. Clear Cache
Go to System → Cache Management and clear the store cache.