How and where do I reset the Apple ID password?
Then how do I access icloud to disable 'find my ipad'?
Sign in to icloud.com/#find with your Apple ID (the one you use with iCloud).
If you’re using another iCloud app, click the app’s name at the top of the iCloud.com window, then click Find My iPhone.
If you don’t see Find My iPhone on iCloud.com, your account just has access to iCloud web-only features. To gain access to other iCloud features, set up iCloud on your iOS device or Mac.
Click All Devices, then select the device.
Click Erase [device], then enter your Apple ID password. Because the device isn’t lost, don’t enter a phone number or message.
If the device is offline, the remote erase begins the next time it’s online. You’ll receive an email when the device is erased.