Change parental pin without Childs phone

Hey there, and welcome to Apple Support Communities davidfrombazza,

We can certainly understand your concern and can help provide some insight. We recommend checking out these steps for more information on how to use parental controls.

" Set Content & Privacy Restrictions

1. Go to Settings and tap Screen Time.
2. Tap Continue, then choose "This is My [Device]" or "This is My Child's [Device]."

• If you're the parent or guardian of your device and want to prevent another family member from changing your settings, tap Use Screen Time Passcode to create a passcode, then re-enter the passcode to confirm. In iOS 13.4 and later, after you confirm your passcode you'll be asked to enter your Apple ID and password. This can be used to reset your Screen Time passcode if you forget it. 
• If you're setting up Screen Time on your child's device, follow the prompts until you get to Parent Passcode and enter a passcode. Re-enter the passcode to confirm. In iOS 13.4 and later, after you confirm your passcode you'll be asked to enter your Apple ID and password. This can be used to reset your Screen Time passcode if you forget it. 

3. Tap Content & Privacy Restrictions. If asked, enter your passcode, then turn on Content & Privacy.

Make sure to choose a passcode that's different from the passcode that you use to unlock your device. To change or turn off the passcode on your child's device, tap Settings > Screen Time > [your child's name]. Then tap Change Screen Time Passcode or Turn Off Screen Time Passcode, and authenticate the change with Face ID, Touch ID, or your device passcode. "

For additional information, check out this link: Use parental controls on your child's iPhone, iPad, and iPod touch - Apple Support

Kindest regards!