Hello,
By default, there is no any option to hide the feature image in post or page. But you can achieve that from CSS code. Please follow the steps and instruction to do that;
Go to Dashboard > Appearance > Customize > Additional CSS > Copy and Paste below CSS and click publish button.
// For page feature image
body.page.page-id-72 article.hentry .post-thumbnail{
display: none;
}
// For post feature image
body.single.postid-72 article.hentry .post-thumbnail{
display: none;
}
Note: The “page-id-72” and “post-id-72” classes are dummy. You can find the classes form the page url.
Thanks.