How can I remove this notification? Sorry repairing at Apple was too expensive for me

I found this on ZDNet.com regarding your question.

If a display isn't genuine the Important Display Message appears on the lock screen for four days and in the Settings app for 15 days. 

You don't. You used unauthorized parts and left some needed ones out.

Apple will not touch the device.

Absolutely. They could also develop a true shatter proof screen. Just depends on which scenario is more profitable I guess.