Why are you wanting to dispose of? Clay is a very nutritious soil just needs a lot of grit and compost worked into it to open it up.

What Mg said, but if you must dispose of some, take it to your local tip.They should have a large container especially for soil.

How would you separate clay from its inclusive soil substrates?

Good question Loosestrife

Depends on your garden Loostrife! When I was small part of our garden had completely solid yellow clay a little way down - in fact I was allowed to dig some out and make a small pot with it. My amazing mother allowed me to bake it in the oven. Needless to say it was an ugly thick cracked disaster - you live and learn...

Do as I do, heavy clay soil is great for making voodoo dolls. They are great for settling scores.

Thanks all for taking the time to reply to my question.the question is actually on behalf of my mother so I have no answers to your questions.

Well leave the clay alone and get a lot of organic matter and grit dug into the garden!