To disable this message for all of an sqlcmd session, use the -m commandline option:
sqlcmd -m 1 <other options>
To disable this message for a block of code, use the :setvar batch command:
USE [mydb]
GO
-- Disable message for next USE command
:setvar SQLCMDERRORLEVEL 1
USE [mydb]
GO
-- Reenable
:setvar SQLCMDERRORLEVEL 0
...