The command QVUser() gives you the current Qlikview user logged in as mentioned in the Section Access. And to hide a sheet, a simple solution would be Goto Sheet Properties-> Layout and then write an expression something like if (User = 'ABC',0,1), here when you do 0 it hides this sheet for him and if its not then 1 which means show sheet. Please work around this and you might find the solution you are looking for.
