You can use SORT to eliminate bytes from your sequential file.
Let's assume the following format:
Employee ID Bytes 1 - 10
Employee Name Bytes 11 - 40
Employee Address Bytes 41 - 70
We want to eliminate the Employee Name. We want to copy the first 10 bytes, skip the next 30 bytes, and copy the last 30 bytes.
The input sequential file is 70 bytes and the output sequential file will be 40 bytes.
Here's the SORT JCL to perform this task. You'll need to modify the JCL to conform to the standards of your mainframe shop.
//EXAMP JOB A400,PROGRAMMER
//COPY EXEC PGM=SORT
//SYSOUT DD SYSOUT=*
//SORTIN DD DSN=SMF.DATA,DISP=SHR
//SORTOUT DD DSN=SMF.COPY,DISP=(,KEEP),SPACE=(CYL,(2,5))
// UNIT=SYSDA
//SYSIN DD *
OPTION COPY
OUTREC FIELDS=(1,10,41,30)
/*
//
The OUTREC statement says to copy starting from byte 1 for 10 bytes, and from byte 41 for 30 bytes, for a total of 40 bytes.
Here's IBM's DFSORT manual for more information.