If you paid $xx, just drop it. If you paid low $xxx, you might want to contact them and explain that you bought without realizing it being a well-known trademark, offer to give it to them indicating that you'd appreciate being reimbursed for actual cost with proof.
If you paid $xx, just drop it. If you paid low $xxx, you might want to contact them and explain that you bought without realizing it being a well-known trademark, offer to give it to them indicating that you'd appreciate being reimbursed for actual cost with proof.