write off

verb

1. To reduce the book value of (an asset) to zero.
2. To record (an expenditure) as an expense.
3. To remove a portion of a debt or an amount of an account owed, counting it as a loss (as a gesture of goodwill for example).
4. To record a notional expense such as amortization or depreciation.
5. To treat as a write-off, a total loss, especially something damaged beyond economic repair.

   “The '800' received substantial collision damage, while the High Speed Train power car was written off.”

6. To assign a low value to (somebody or something).

   “When Katya was injured, he wrote off the team's chances in the finals.”

   “Hey, don't write yourself off yet / It's only in your head, you feel left out”