If you wish to delete users, use the .-user command..
However, you really should'nt have to do that just to get hostmasks and flags in order (except maybe in very rare cases). Use .chattr, .+host, and .-host instead..
In any case, since bot does'nt see you as opped, that's why it fails for you.. if you think you are opped, channel or your bot is desynced.
Also, your other staff (those that are shown as opped by your bot), which of the errors do they get?