It's not possible to remove NFTs from your account without your signature.
It is however possible for us to blacklist a collection from AtomicHub, which hides it from view on AtomicHub.
The underlying NFTs on the blockchain are unaffected though. You can go to your Inventory, then to Account Settings and enable showing blacklisted NFTs. This will make them show up for you (however it won't display their images).
Unfortunately, since market purchases are decentralized and irreversible, we can’t help you get your tokens back, and we can't offer you any refunds for this issue. It's your own duty to do background checks on the seller and the collection itself before buying anything. Please try to be more careful in the future and always do some research before buying anything.