Hi @yingjie,

Unfortunately this is browser native behaviour and there isn't much you can do about it:

https://stackoverflow.com/questions/25937212/window-close-doesnt-work-scripts-may-close-only-the-windows-that-were-opene

For security reasons scripts are only allowed to close windows that they opened themselves.

Here's an excerpt from the Nintex help:

https://help.nintex.com/en-US/k2five/userguide/5.5/default.htm#Create/K2Designer/Rules/RuleActions.htm?Highlight=close%20window

Regards,

Ernie