# subtract method | |
*[<Null safety>](https://dart.dev/null-safety)* | |
void subtract | |
(int delta) | |
_<span class="feature inherited">inherited</span>_ | |
<p>Subtracts <code>delta</code> from the value of this metric.</p> | |
## Implementation | |
```dart | |
void subtract(T delta) { | |
_writer?.subMetric(index, delta); | |
} | |
``` | |