how to to manually kill tween in Godot 4?

i'm trying to make a rpg-style dialogue system in godot 4 by using tween.

here is my code:

var isrun = false

func addText(next_text):
    isrun = true
    maintext.text = next_text #maintext is label node
    maintext.visible_ratio = 0
    var tween2 = create_tween()
    tween2.tween_property(maintext, "visible_ratio", 1, len(next_text) * readFast)

func _on_button_pressed():
    if isrun == false:
        addText("texttexttext")
    elif isrun == true:
        $addText.tween2.kill(self)
        isrun = false   

this is what i expected:

when i press button:

if it is the first time that i pressed the button: execute addText function

or if it is the second time that i pressed the button: kill tween2 in addtext funtion

excute addText function works well, but kill tween2 doesn't work

how can i solve this problem?

Judging from the example code you provided the problem is one of scope. You create the tween2 variable in the addText function. Therefore it should be undefined/null in the _on_button_pressed function. Add a "global" (in your script) variable that holds the tween and try creating the tween in your _ready function.