If you want your data to remain in the attribute table but not visible in your map, you can accomplish this (without duplicating your data classes) with “unique values” in the symbology settings. For the unique data you want visible, simply choose the symbology of your choice; for the rest of the unique data, setup the symbology with something not visible or do not include/remove it completely from the symbology class.
Remember, if you choose this symbology option (as opposed to a definition query which would remove data from your attribute table), although your data will not be visible on the map, the data will still be editable.
Here’s some documentation from ESRI on setting up the symbology. Hope this helps.
