Step 1: Enable usb Debugging
Step 2: Now Go to settings > security and Privacy and then Device administrators and disable Retail Mode and HWRetail Assistant.
Step 3: Now Connect Phone with USB Cable.
Step 4: Now install ADB drivers if you don’t have just google it.
Step 5: Now Open Command Prompt and enter these commands.
Step 6: Type in command prompt
C:\adb> adb devices -l
it will show result like
XX0000000000 device product:CLT-L29 model:CLT_L29 device:HWCLT
C:\adb>adb shell cmd package uninstall -k –user 0 com.huawei.retaildemo
C:\adb>adb shell cmd package uninstall -k –user 0 com.huawei.experience.ec
If the first command failed don’t worry just try second command and press enter.
From these commands, the demo video will be removed and stop playing again and again.