In the upper left corner of your Huawei P8 appears the operator name in the status bar. So you know always in which mobile network you are just logged in. Would you like that this place remains free and the network provider name is not displayed, then you can change this setting as follows:
Open from the start screen of the Huawei P8 the menu and then:
Settings --> All --> Display
In this submenu scroll down a bit until you see the option "Display carrier name".
You can now activate or disable the option. Disable the function to hide the network operator name in the status bar of your Huawei P8 when the screen is unlocked.
You know now how to hide the network operator name in the status bar of your Huawei P8.