If you delete your account, yes it would be multiaccounting. But if you just want a name change you can ask osu!support they might give you one for free. otherwise you can enter a competition for supporter which comes with 1 free name change. Or you can just buy it... https://osu.ppy.sh/home/support
Why would you wanna replace your current one in the first place? There's not much of a benefit for doing it, more so you'd risk getting banned from violating the rules.
Well if you just wanna delete your account, you can contact the following and state your reasons as to why. Your reason must be valid though.