Hey @useraa4fQ1gIdw, I hope you are doing well.
From what I'm reading and seeing from your post, you're wanting to hide the status bar? (The top bar that has the clock, notifications, network info, battery, etc...) Is that correct?
If so, natively you cannot hide the status bar. But it is possible using an app called SystemUI Tuner from Google Play but this also requires ADB to set up.
If you're referring to the AT&T logo that is persistent on the top left, this can be hidden by downloading Samsung's Good Lock app from the Galaxy Store (here.) Once Good Lock is installed, open it. You'll see an option called Quick Star. Press Quick Star and install it. After it is installed, go back into Good Lock and open Quick Star. Once you've opened Quick Star, press on the "Visibility of Indicator icons" option. In there, you'll see the first 3 toggles in the top section. Uncheck those and that should remove your carrier label.
If you need further assistance with this matter, please feel free to reach out.
I hope this helps! Have a great rest of your day.
Most definatly looks like it is caused by your choice of background image. Either change the background image, or crop the image to where the white lines are gone in the original photo.