Tim
this does not sounds like a good idea. You’ll get the whole realtor community made at you if you send direct mail to owners then ask them to cancel their listing. If you bring the buyer to the table while they still have an active listing then they still owe the realtor a commission ( even if you find the buyer)
You could be sued by the agents for tourteous inteferrence of a contract.
It’s better to get to these houses before they are ever listed or after the listing expires.
Plan B is to work with the agents. Most will not be receptive but a few will.