keywords-undeclare

In a DASIL script, this "pseudo-command" causes an identifier declared in that script to be undeclared. Only valid for items declared in the top level of that script. You can undeclare variables, types, procedures, etc. Undeclared variables are effectively immediately out of scope and subject to immediate deallocation by the garbage collector.

var i% = 3 ' It's here
undeclare i% ' now it's gone