how to write "exit sub" in javasript???

Me.RegisterStartupScript("PleaseSelect", "<script language=""JavaScript"">" & _
"if (confirm('Are you sure you want to delete this user?')==false) " & _
" alert('Action cancel');" & _
"<" & "/script>")

this is the code that i have and i need to add in the "exit sub" to this code to let the function complete.
by using this code without the "exit sub", no matter the user click the ok or cancel button it wil auto delete
the data also.

Use

This will exit the function without performing any more actions.