We have not replaced it yet, but can I retire it from the Balance Sheet now, as it is fully depreciated? Or do I have to wait until it is carted off to the landfill to retire it?
If the asset (refrigerator) is still "in use", then you really should leave it in the assets section. As an example, lets say you sell that old fridge, or if you take it to the metal recycler and they give you say, $10 for it. Since it was already fully depreciated, any amount you sell it for (even $10) is reportable/taxable income. You'd report the sale of that asset in the same assets/depreciation section where it's listed.
If you end up carting it off to the landfill, then you still need to "show" it's disposition on the SCH E in the assets/depreciation section. You just indicate that you stopped using the asset in whatever tax year. Then when asked if "special handling" is required, you select YES. It's disposition as a non-taxable transaction will then be "indicated" (for lack of a better term) on the tax return. Then, if it's imported the next tax year, you get delete it from the assets section then.
Otherwise, if an asset just "disappears" from your return, it "could "have the potential to raise eyebrows. Now I've never seen that happen. But just because I've never seen it, doesn't mean it hasn't happened, or can't happen. Though in my opinion, I think it would be extremely rare.
