forgot password for guided access

I will be able to assist you with this for this you would have to restart your iPad. And you would get the Lock Screen enter the passcode of your iPhone and not the one of guided access and get into your iPad. When it will open it will go to the Home Screen then go settings>accessibility>Guided Access and turn off guided access and passcode this will help you reset the passcode.

If your iPad doesn’t open to the Home Screen and open to the same guided access we need to reset the settings to factory default you need to follow the steps at https://support.apple.com/en-us/HT204306#recovery and recover it and then you will be able to use it as usual