Theres two dif ways i think you can do tha
you dun really need the lvl indicater if you have the isop in second line

on 1000:TEXT:!rembot *:#:{
  if ($nick isop $chan)

Theres this way[didnt test im in school]

on *:TEXT:*:#:{
   if ($nick isop $chan)
   var %c = $1 | goto %c
   :!bot | bs assign # $2 || /notice $nick Bot $2 assigned to $chan | halt
   :!rembot | bs unassign # $2 || /notice $nick Bot $2 unassigned from $chan | halt
   :%c | return
}

then theres this way

on *:TEXT:*:#:{
   if ($nick isop $chan)
   if ($1 == !bot) { bs assign # $2 || notice $nick Bot $2 assigned to $chan | halt }
   if ($1 == !rembot) { bs unassign # $2 || notice $nick Bot $2 unassigned from $chan | halt }
}