[GAP Forum] Removing identifiers in GAP

[Bulutoglu Dursun A Civ AFIT/ENC]

	Dear GAP Forum,
	I was wondering if it is possible to remove user defined
identifiers in GAP.
	If I type "a" right after I start the gap session I get the
message "Variable 'a' must have a value". Then I make the following
object assignment:
	"a:=4;" 
Then if I type "a;"
I get "4". Now how can I undo this assignment? In other words what am I
supposed to do other than logging out so that I get the message Variable
'a' must have a value?