iPad is locked on someone's iCloud

Return to the original owner, unless you are knowledgeable as to who they are, will not be possible. Apple will not disclose any ownership data - even it they have access to it.

All you can do is return the iPad to an Apple Store for responsible recycling.

Here are the Apple support pages that outline the Activation Lock - and the only mechanisms by which it can be turned off:

https://support.apple.com/en-us/HT201365

https://support.apple.com/en-gb/HT201441

As you will discover, unless you are the owner of the AppleID that was last used to activate the device, or unless you can secure the cooperation of the previous owner, you’ll not be able to defeat or bypass the Activation Lock. Without documentary evidence that you are the original owner (such as sales receipt showing the serial number), Apple won’t assist - and nobody here will be able to help you.

Sorry, that’s the bottom line. There are no other options.

I guess that if it really matters that much to you, it remains possible that you could send the iPad Apple for recycling - but this would be at your cost. Just Google “Apple Recycling Services” for further information.

As already stated, all you can do is return the iPad to an Apple Store for responsible recycling. Alternatively, hand over the device to your local Police department.