The `--clear-cache` option removes caches.

**The scan is not performed.**

```
$ trivy image --clear-cache
```

<details>
<summary>Result</summary>

```
2019-11-15T15:13:26.209+0200    INFO    Reopening vulnerability DB
2019-11-15T15:13:26.209+0200    INFO    Removing image caches...
```

</details>
