No, you can't do so, though parental controls will disable some features.
I think we've needed more show/hide type customisations for some time to simplify the menu system.
For example I rarely use YouTube and don't use Flickr/Vimeo at all, nor teh US sports streams that are of little interest to me - I'd love to hide most of the clutter I don't use, and be able to rearrange the rest. Pre icon interface at least had things in column based categories, whereas now they're just consecutive items.
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I don't think you'd be alone in doing so!
I know this was originally posted quite awhile back, but you can indeed now do this with the latest Apple TV update (5.X). The hiding of menu apps can be done within the Parental Controls area under General (look towards the bottom half). You can also rearrange the menu icons. Here is the Apple Knowledge Base article detailing: