Close menu bar menu with applescript tell application "System Events" to tell process "SystemUIServer"
    tell (menu bar item 1 of menu bar 1 where description is "system sound volume")
        click
    end tell
end tell


will open the sound menu bar item, but I want to delay one second then close it.

I tried:

tell application "System Events" to tell process "SystemUIServer"
    tell (menu bar item 1 of menu bar 1 where description is "system sound volume")
        click
        delay 1
        cancel
    end tell
end tell


but that didn't work
You almost had it.  This works for me.

tell application "System Events" to tell process "SystemUIServer"
    tell (menu bar item 1 of menu bar 1 where description is "system sound volume")
        click
        delay 1
        key code 53
    end tell
end tell