With DFSORT. Exactly how you would do it depends on exactly what you want to do (e.g. if you want to delete the first 10 records, you can use SKIPREC=10; if you want to delete records based on a condition, you can can use OMIT, etc).
If you're not familiar with DFSORT and DFSORT's ICETOOL, I'd suggest reading through "z/OS DFSORT: Getting Started". It's an excellent tutorial, with lots of examples, that will show you how to use DFSORT, DFSORT's ICETOOL and DFSORT Symbols. You can access it online, along with all of the other DFSORT books, from:http://www.ibm.com/servers/storage/supp ... tmpub.html