The only way you can achieve this will be by creating the customer account yourself in the first place.
Once you created each customer account you can create dedicated user access for each operator on the customer account without giving them access to the chatbot builder (and any other functions)
Go to My Company in the left menu
2) Create the Role you want your customer to have within their account (leave the Chatbot Builder unchecked)
Your customer can now create their own chat operators but use only the Roles you have previously created on the particular account.