|SQL*Plus User's Guide and Reference
Command Reference, 49 of 52
Deletes one or more user variables that you defined either explicitly (with the DEFINE command) or implicitly (with an argument to the START command).
Refer to the following for a description of the term or clause:
To undefine a user variable named POS, enter
To undefine two user variables named MYVAR1 and MYVAR2, enter