Well that's a problem.
If you bought it second hand, you need to contact the seller and ask them to remove it from their inventory.
Unfortunately support cannot remove it for you, the most they will do is inform which organization the MR is linked to.
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
Please, if this post was useful, leave your kudos and mark it as solved.