@Francois686
If it is setup well from the beginning, then the "superhost" is the co-host of your accommodation (which is listed onder your account) and now can be removed as a co-host.
If the listing is setup under the account of the "superhost", then it must be deactivated and you have to create a new listing under your account. Then all reviews regarding the listing will be lost.
(asuming you do not want to become the co-host of your own accommodation, listed elsewhere...)
Best regards,
Emiel