When posting on Facebook, you will notice the "Published by Social Slingshot" label on the post similar to this:

At this time, this label is required as part of Facebook's API agreement with third party companies such as Social Slingshot. This label is only visible for page owners and not to regular audience. 

What the audience will see:

As you can see, the "Published by" is not visible anymore. However, if you still wish to modify this and rename it to your brand, this is possible through white labeling. You may contact us for more information.