How to delete old data from a table in Microsoft SQL database

Hi, i have a table and i want to delete only the old data. from 1 to 15000
i used the command:
DELETE FROM EyeClinic.dbo.tbtrnBillDet WHERE intDetBillNo=400
but it only delete one record at a time
is there a way i can delete the data from 1 to 15000 in one command??
i know i can select it and delete it but it will takes time.
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