Hey ,
Unfortunately, I did not see any direct way to change the reflection to block certain aspects from within the reflection sphere, or from the actual environment. However, you can go into the texture, which is nested under materials and actually change the roughness of that texture. When you do that, there is less of the reflections actually appearing on the “floor” of your project. I’ve attached a few screenshots for you to see what I’ve done. You do not have to set the roughness as high as I did, I simply did that to test the reflective nature of the texture afterwards.
This is the section where I went to change the roughness of the texture:
This is what you’re looking for, once you’re inside of the texture blueprint:
This scene is a text actor not reflecting, even though the refection capture is placed:
Hopefully this will help you achieve what you’re looking for. If not, please feel free to comment back and I’ll be happy to investigate this further for you. 
Cheers!