If I have an asset that I purchased for $4,000 and I have depreciated it and recorded $3,500 on my balance sheet, if I do not have the asset anymore, how do I write off the balance of $500?

Would I credit the asset for $500 and debit the A/D account for $500?

Need response ASAP

If you only remove $500, what are you going to do with the balance that will remain in those two accounts?

You need to remove the entire amount of the asset out of its account and the entire amount of the accumulated depreciation out of its account. Not just $500.

That will create a $500 difference, which is your book value. If you are just disposing of the asset (not selling or trading it), that's Loss on Disposal of Asset.