Disable Cart and Button: Add to Cart on:

Header page
Header Top Bar
Modules: Featured, Latest, Special, Bestseller
Product page
Category Page
Search page
Manufacturer page

Install:
Intall: Disabled_cart.ocmod.xml file: Goto admin->Extensions Installer->Install Disabled_cart.ocmod.xml

Refresh Modifications Extensions: Goto admin-> Modification Extensions-> Click Refresh button