how can you delete friends from your friends list? (not best friends)

[battler]

Hi all, i deleted my old save because i wanted to restart, my friends have visited my old save’s island before. But now i made a new save and my friends are telling me they have me twice on their friends list and have no way to delete the old save because it doesnt give them to option to just “make best friend” is there a way for them to delete the old data?