Hi @Mai Quoc Khanh,

I hope you are well today and thank you for your question.

First question: How to hide meta information in mega menu item (I have described as in picture)

You can achieve it by adding the following CSS code in the Custom CSS code option of your theme on the below path.

Admin Area -> Appearance -> Theme Settings -> Custom Code -> CSS Code

#header-navigation .tab-content .post-meta {
    display: none;
}

The second question: How to hide a specific meta in posts on the mobile interface but still on the desktop.
For example, I want to hide the comments on mobile devices, but it will still show on my desktop and other devices.

You can hide it on mobile using below custom CSS code.

@media (max-width: 550px){
#content article .post-meta a.post-comments {
    display: none;
}
}

Best regards,
Shufflehound team

To hide read time on mobile, just change the above shared custom CSS code as below.

@media (max-width: 550px){
#content article .post-meta a.post-comments,
#content article .post-meta  .post-readtime {
    display: none;
}
}