No, if you remove any code, it will be gone and not available for every user.
To limit to administrator only, you need to wrap with this function. https://codex.wordpress.org/Function_Reference/current_user_can
Sorry, I cannot assist in customization, my employment agreement forbids me to do so, I will not get paid for any customization assistance.
Since you mentioned that no one replies your request via our services page. I suggest you do a job posting on http://jobs.wordpress.net/ I am sure you can easily hire someone to do the customization.
Sorry, That’s all I can do for this issue.