Can we apply restrictions on New and Edit default buttons in zoho crm?

Can we apply restrictions on New and Edit default buttons in zoho crm?

Hi, 

I am working on a project in which I am managing inventory of products by adding/subtracting the quantity ordered from total quantity of Products and on the basis of Status of product. 

I have made two custom buttons New Quotation and Edit Quotation and I am handling my tasks from custom API using PHP.

Now I want to restrict to user, that he/she use only my custom buttons, not the default New and Edit buttons.
I have tried to do this by removing permissions of Edit, Create from Setup/Roles, but then it does not allow us to edit , Create records from Custom API as well.

How can I do my task?

Any help will be appreciated.