windows - How to rename last part of file name

I have a number of files to rename, I want to remove _thumb in existing name.

Eg: 00700008_thumb.jpg

    00800104_thumb.jpg
    01200004_thumb.jpg

I want to rename the above files as:

Eg: 00700008.jpg
    00800104.jpg
    01200004.jpg

Using below code how to separate the part.

@ECHO ON

SETLOCAL ENABLEDELAYEDEXPANSION
SET SourceDir=F:\Square.....

FOR /F "TOKENS=1-3 DELIMS=. " %%F IN ('DIR /B /A-D "%SourceDir%\*.jpg"') DO (
  SET "part1=%%~F" 
  SET "part2=%%~G" 
  SET "part3=%%~H"

  REN "%SourceDir%\!part1! !part2!.!part3!" "00!part2!.!part3!"
)
GOTO EOF

How can I rename the files?

Answer

If your issue is to rename those files, according to your examples, you could just cd to the folder you want and issue the following command:

for /F "useback tokens=1 delims=_" %I IN (`dir /B /A-D *.jpg`) DO (ren %~I_thumb.jpg %~I.jpg)