array unset arrayName ?pattern?
Unsets all of the elements in the array that match pattern (using the matching rules of string match). If arrayName isn't the name of an array variable or there are no matching elements in the array, no error will be raised. If pattern is omitted and arrayName is an array variable, then the command unsets the entire array. The command always returns an empty string.
Note that this is only available from Tcl v8.3 onwards; see Arrays / Hash Maps for methods of clearing arrays in earlier versions of Tcl.
See also: