> Firebase控制台中的>项目设置>选择应用>高级选项>删除此应用。

I tried out new version of Firebase. I have created new project. Added there necessary apps. After that I added the test app, which I don't need any more. But I could not find a button that can remove this test application without deleting the entire project.

You can delete apps from a project via Project Settings > Select App > Advanced Options > Delete this app on the Firebase console.