Thanks for chosing Optometry WordPress theme. There are two rows on Header top one is Top Bar and the following which have logo and navigation is header. Search box is in Top Bar while the Cart button and appointment button is in header >> navigation.
Please sign in WordPress admin >> Appearance >> Customize Click on Top Bar and if you are having concern about right side of Top Bar please open that and click on checkbox Disable Search Box. If you want to edit the Social icons then go back in Top Bar and go to Social Icons then disable the icons you don't want to display.
For the Cart button on Header, ou should deactivate the WooCommerce plugin if you are not using WooCommerce. If you are using WooCommerce for your optical Shop WordPress theme then you should let me know that would be a customization in theme a little to disable that button. Thanks.