Get rid of screen time :C

Two scenarios.

1. you used your Apple ID when setting the Screen Time passcode. If you have forgotten your Screen Time passcode – Apple Support (UK)
2. You didn't use Apple ID to set Screen time password. You need to move all your data and photos somewhere safe, wipe the phone, and start again.

See this Apple article: Use Screen Time on your iPhone, iPad, or iPod 

Use Screen Time on your iPhone, iPad, or iPod touch - Apple Support

Settings, Screen Time, Turn off Screen Time.

What if you forgot the passcode? Aka I did.