I disabled iCloud but the device stills hows up

i currently traded in an old macbook and gave my mom my imac. I bought a new mac pro but there is an issue with find my mac. i disabled find my mac on the imac and the macbook was wiped by bestbuy. however, both computers still show up on my find my mac app. it's not a huge deal but it's just annoying seeing 2 devices in there that will never actually be found. any ideas on what to do?