1. If u need to delete Only Quotes between two specified Dates, then use Script by MasterMind or Trash , wl upload morrow if u cud not find it on ur own.
2. If u need to delete any Symbols , Best option is to manually open the DB & delete the unwanted Symbols manually.
3.And plz dont forget to delete "Broker.Master" file inside the DB , dont worry this file wl b auto Re-Generated on ur nxt use of the DB
4.Plz make a BackUp copy of ur Original DB b4 u embark on ur Delete-Journey. U may delete the BackUp once u r happy with the Cleaned DB and ensured working.