Hey rileyxrose,
Thanks for using Apple Support Communities. We'd be happy to help out. We understand you're having trouble disabling Screen Time on an iPad managed by your school so you can sign into iCloud.
It's very possible that this is by design, as the school may not want you to login with your own personal Apple ID account. It's likely that it's not yours or your father's personal Apple ID that's associated with this device and instead one managed by your school. You should work with them and their IT department to get a solution if you're unable to resolve the issue using these steps:
How to reset the Screen Time passcode for your personal device
Use the steps below to change your Screen Time passcode on iPhone, iPad, iPod touch, or Mac.
On an iPhone, iPad, or iPod touch
1. Go to Settings > Screen Time.
2. Tap Change Screen Time Passcode, then tap Change Screen Time Passcode again.
3. Tap Forgot Passcode?
4. Enter the Apple ID and password* that you used to set up the Screen Time passcode.
5. Enter a new Screen Time passcode, then enter it again to confirm.
This is outlined further here: If you forgot your Screen Time passcode - Apple Support
We hope this helps out.
Take care!
