Super Admin deleted

Sorry, It’s not mutisite, how can I transfer it to another section?

I tried adding this admin, but it comes lacing some priviledges such as installing new plugins because his role is administrator and not super admin

What should I do?

Regards,

I confirmed now that it’s not multsite useing this code :

if ( is_multisite() )
{
 echo 'Multisite is enabled'; }
else{
 echo 'no';
}

It outputted : no.

So now, As you said, I must not be having a superadmin, but why my administrator accounts lacking some privileges although they are set as administrators?