When you use the ***Azure App Service Deploy*** task in Azure DevOps Pipeline to deploy your application and select ***Web Deploy*** method option, there is an additional option to ***Remove Additional Files at Destination***.
If you check this option, the deployment process will remove any files at the destination where there is no corresponding file in the package that is being deployed.
In other words, it'll remove any left-over files from a previous deployment that are no longer required.
[![enter image description here][1]][1]

[1]: https://i.stack.imgur.com/xSV1G.png

When using the **Azure App Service Deploy** task, **and** you are using the **Publish using Web Deploy** option, there is an additional option to **Remove Additional Files at Destination**.
[![enter image description here][1]][1]
If you check this option, the deployment process will remove any files at the destination where there is no corresponding file in the package that is being deployed.
In other words, it'll remove any left over files from a previous deployment that are no longer required.
[1]: https://i.stack.imgur.com/PVuJx.png