Parameter

logical-name[:]

   Specifies the logical name to be deassigned. Logical names can
   have from 1 to 255 characters. If the logical name contains
   any characters other than alphanumerics, dollar signs ($),
   or underscores (_),  enclose it in quotation marks (" "). The
   logical-name parameter is required unless you use the /ALL
   qualifier.

   If the logical-name parameter ends with a colon (:),  the command
   interpreter ignores the colon. (Note that the ASSIGN and ALLOCATE
   commands remove a trailing colon, if present, from a logical name
   before placing the name in a logical name table.) If the logical
   name contains one or more trailing colons, you must append one
   additional colon to the DEASSIGN logical-name parameter (for
   example, type DEASSIGN FILE:: to deassign the logical name
   FILE:).

   To delete a logical name table, specify the table name as the
   logical-name parameter. You must also use the /TABLE qualifier to
   indicate the logical name directory table where the table name is
   entered.