How do I remove or hide ad unit from adsense account?
You can not delete or remove an ad unit from your adsense account, because to maintain the ad history Google won’t allow you to delete or remove the ad units from AdSense account.
However you can hide it or simply don’t use it. So, if you want to hide ad unit then
Goto Ads > By ad Unit > Click Three dots > Archive the ads you want to hide.