How do i remove the Top Menu?`

Hi,

You can add this to your theme’s CSS:

#top-navigation {
display: none;
}

@wphelpout.com solution will do.

Sorry, but when i switched to mobile layout, the main menu is gone.. can i just remove top menu but keep the main menu?

If you are referring to this theme: https://wp-themes.com/mesocolumn/
There is only one menu as you can see on that page.
Therefore I’m not sure what you mean by “top menu but keep main menu”.

add this extra css after the previous

@media only screen and (min-width:280px) and (max-width:750px){
#top-navigation {display: inline !important;}
}

Sorry , to avoid miss-understanding, like this:
#top-navigation {
display: none;
float: left;
margin: 0px 0px -2px;
padding: 0px;
width: 100%;
background-color: #EF4423;
position: relative;
}

@media only screen and (min-width:280px) and (max-width:750px){
#top-navigation {display: inline !important;}
}

Richie,
If i use mobile, i’m trying to show only “Select Category” and remove “Select Page”

to clarify:
1. Desktop version – remove the TOP MENU
2. Mobile version – remove the “Select Page”

add this

p.select-pri {display:none;}
p.select-pri.sec {display:inline !important;}