Hey, I have made some actors in blueprint and in the editor they have a sprite of a sphere which I cannot remove. How can I do this?
YOU CAN UPLOAD A PRINT SCREEN ?
Thanks a lot! 
So, in case someone stumbles upon this question in the far future and the video is gone: Drag the mesh of your blueprint to the default scene root, to make the mesh the default scene root.
This is not a solution for everyone, since that robs the new root mesh of the capability of having translation of rotation applied to it. If you need that feature, you must have a scene root, and that annoying ball is always in the way.
If anybody has an idea how to get rid of this, please post.
Hint to Epic: there should be a flag to show the ball or not in the editor
My solution is to replace the scene with two arrow components that are hierarchical. Make the top one invisible, then you can use the second level arrow to indicate whatever direction makes sense in your scenario and then add meshes etc under that second arrow.
If you prefer to keep your meshes and other components as children:
In the blueprint editor, click Add Component, choose Scene, then drag that over the default root component to replace it. Boom - the white ball is gone 
As per its description: Scene component has a transform so you can do whatever you want with it in terms of translation/rotation, but it does not render in any way and has no collisions, so it’s perfect as a container or a dummy component.
Great solution! Thanks a lot, but i don’t understand why it works, i thought default scene root was already a scene component but it doesn’t matter since it works