URGENT!!! What is the double entry for writing off trade payables?

Question

The payables are long unpaid and supplier will not ask us for payment.

Answer 1

You reverse part of the original entry. Presumably when you first made the purchase long ago, you
Dr Purchases (or Inventory)
Cr A/cs payable

So now if you're very sure the supplier won't sue you for payment, you reverse partly the above. By now the merchandise must have been sold by you, so you need to
Dr A/cs payable
Cr Cost of goods sold

Answer 2

Trade Payables A/c Dr
(Name )
To Other Income A/c

Answer 3

If you do as per sandy said, you will be reducing the cost of goods sold this year by a transaction which does not belong to current year, thereby distorting the actual profit & Loss figure of current year.

Therefore, better entry would be:
Dr. Trade Payables
Cr. Profit/Loss A/C

This entry will not affect the profit & loss of current year and give a true picture of company's affairs.