How to remove the important display massage ?

You cannot remove the message manually. You will see a notification on your Lock screen for the first 4 days that you use your device and in the Settings app for 15 days. After that period, you can find the notification by going to Settings > General > About

Axel F.

Kicitmiaoz1112 Said:

"after I upgraded my iOS, become like this, and I never changed any parts of screen, I’m using the original and never been repair yet this iPhone "

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Did you Ever Get a Replaced Screen?:

If you are getting notifications about a screen being ungenuine, then ask the person who replaced it to replace it once more, but this time with a genuine screen. The person should have known better. Elsewise, you'll continue getting the notification.  Learn More here: About Genuine iPhone Displays - Apple Support