Corrected some bad english. "Signalman" replaced to "Reporter" and "Remove" replaced to "Delete" in the whole plugin (including messages.yml, the command /reports removeall, the permission tigerreports.staff.remove and the database tables). [The tables "tigerreports_reports" and "tigerreports_archived_reports" of the database must be deleted. Old reports will be lost]
Moved permission to change statistics of players from tigerreports.staff.advanced to tigerreports.manage permission (thanks to @SKVIRLSOV for the suggestion).