write off
To remove (an amount) from a business record; cancel (a debt); accept as a loss.
If a customer dies when he owes the store money, the store must often write it off.
To accept (a loss or trouble) and not worry anymore about it; forget.
Mr. Brown had so much trouble with the new TV set that he finally wrote it off and bought a new one.
Jim's mistake cost him time and money, but he wrote it off to experience.
To say that (something) will fail or not be good; believe worthless.
Just because the boys on the team are young, don't write the team off.
write-off
A loss.
This last unfortunate business venture of ours is an obvious write-off.