how to remove the LOGFILE and perform some operations from cmd prompt

SELECT name,recovery_model_desc FROM sys.databases
and check whether the database is 'FULL' mode or 'SIMPLE'..if it s FULL we have to remove the LOGFILE of database.
go to database ...> detach.. next goto logfile and rename it..of that database
again we have to attach the only .mdf file (instead of .mdf and .ldf files to database)
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sqlcmd -?
we can change the sqlserver sa password from cmd prompt very easily
EXEC SP_PASSWORD NULL,'venki','sa'
GO