Can you clarify what you mean by "expenses already deduct income"? You will report your income in Schedule E, then separately report and deduct expenses. You can't deduct income. If you mean that you have enough expenses to offset your income, you still should take the depreciation expenses, because if you don't you will need to recapture the missed depreciation when you sell (essentially permanently losing the deduction). So, do not delete the rental asset.
