write off

To reduce the book value of (an asset) to zero.

To record (an expenditure) as an expense.

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).

To record a notional expense such as amortization or depreciation.

To treat as a write-off, a total loss, especially something damaged beyond economic repair.

To assign a low value to (something).

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