How to close terminal window launched using Apple Script in Mac app

Question

I have a Mac application. This app is executing following apple script using executeAndReturnError method of NSAppleScript class:

set tempDir to path to temporary items as string
set tempFilename to tempDir & "Test_Log.txt"
set tempFilePath to POSIX path of file tempFilename
set wasRunning to application "Terminal"'s running
tell application "Terminal"
    if not wasRunning then
        close front window saving no
    end if
    set mytab to do script "ls -l" & quoted form of tempFilePath
    set title displays custom title of current settings of mytab to true
    set custom title of current settings of mytab to "Test Log"
    repeat until busy of mytab is false
        delay 1
    end repeat

    if ((count of windows) = 1) then
        quit
    else
        close (every window whose name contains "Test Log")
    end if
end tell

When above apple script is executed by my app for the first time, terminal window remains open. When above apple script gets executed subsequently, terminal window is closed (as expected).

Can anyone please assist me on how can I close the terminal window always.

Please note that, I want to close the terminal window that has been opened by my apple script mentioned above. If there is already other terminal window opened (manually by user) before running above apple script, then this manually opened window should not be closed.