How do I turn off parental control

Settings > Screen Time > Turn off Screen Time

If your parents use a third party parental control app does it let you delete it? In settings, go to screen time, and see if it will let you disable it... If this doesn't work, open settings, general, reset iPhone https://support.apple.com/en-gb/HT201274. Yes you will lose your data, but you can't really do anything about it because the parental controls are probably tied into your device.