Is there a way to run sqlcmd to get query output without showing the number of rows affected?

I think you might want the "SET NOCOUNT ON" option. Your SQL script will look like:

 set nocount on  
 select x, y, z from agent  
 set nocount off  

And the results set will be:

 24 aingles1         creablegs            
 25 tbails12         bull2dog12           
 26 jtaylor3         Leandon62606         
 27 forrestw1        nuke19211    

Minus the count of rows line at the end.

sqlcmd -S svr -d db ... | findstr /v "rows affected"

findstr is built into the OS and is simliar to grep. See findstr /? for more options.

To remove a column, use cut.exe tool. So you could run:

sqlcmd -S svr -d db ... | cut -c10-

This would only output from character 10 onwards, thus removing the line numbers. Adjust the number 10 accordingly. You could also try fields:

sqlcmd -S svr -d db ... | cut -f2-

This would only output fields 2 and onwards (to the right).

I add the following code block to the beginning of the query itself to remove all messages when using sqlcmd.exe to export results to CSV.

-- Suppress warnings and messages like (2 rows effected)
SET ANSI_WARNINGS OFF;
SET NOCOUNT ON;
-- SQLCMD.exe batch command
:setvar SQLCMDERRORLEVEL 1
-- To Reenable
--:setvar SQLCMDERRORLEVEL 0
/**********************************************************************************
**  DISABLING WARNINGS AND MESSAGES
**  Disable "Changed database context to 'DatabaseName'." message in the CSV file when using 
**  SQLCMD.exe. You'll get a syntax error when executing this query in Management 
**  Studio if SQLCMD Mode is not enabled [Query] --> [SQLCMD Mode].
**  :setvar SQLCMDERRORLEVEL 1 is used to disable messages like (152 Rows affected).
**********************************************************************************/