If you don't want certain Items to show for your online ordering, you can simply hide them in YourMenu so they do not display! You can also hide Items from showing in your POS, but still show them online.
To hide/un-hide an Item:
On the YourMenu dashboard, go to Menu > Items and locate the Item you wish to edit
Click the Edit button next to the Item
On the top of the edit screen, change the Availability to the correct choice
Not Available = Won't show on POS or online
Online Only = Will show online, won't show on POS
POS Only = Will show on POS, won't show online
Both = Will show on POS and online
Click Save
To hide/unhide multiple Items at once, you can click Quick Edit on top right of the screen. Once done, click Save!