>>>Some of our sellers get brand approved with trademark document also with Brand Authorization.There are two things you can do:
1)You can send your trademark document along with manufacturer Authorization letter to request amazon for remove any listing using your brand. In some case amazon still accepting it.
2)If any seller selling your brand of product and you own Trademark along with authorization letter asking to remove their listing. If required you may also warn them to sue.
If you have trademark and manufacturer authorization letter and some other sellers try to come in to your listing then you can provide trademark document to amazon which will lock all your listing for existing sellers.