chop part of the string

[marist89]

SQL> l
  1  select
  2  substr('xyxxyyxxxyyyxy',
  3     instr('xyxxyyxxxyyyxy','xy')+length('xy'),
  4     length('xyxxyyxxxyyyxy'))
  5* from dual
SQL> /

SUBSTR('XYXX
------------
xxyyxxxyyyxy