unset - is used to remove variables or functions.

syntax
$ unset <var-name>

$ VAR1='welcomt to linux'
$ echo $VAR1
$ unset VAR1
$ echo $VAR1

$ export ILUGC=foss
$ printenv ILUGC
$ unset ILUGC
$ printenv ILUGC



regards,
T.Dhanasekar