You can reduce jpeg size with MS Paint. It is already installed on Windows systems, nothing to buy, download or install. Here are the steps:

1) Open up the folder that contains the jpeg file
2) Right click on the jpeg file to bring up the options menu
3) Select OPEN WITH and then select PAINT
4) The image with then appear in PAINT and then all you do is select FILE and then SAVE

This will not change the dimensions or image quality of the jpeg, just make the jpeg smaller if possible. I edit lots of jpegs for my website and after rotating and cropping the image with an image editor, I reduce the image size with PAINT. Typically an image will be reduced to 20 to 25% of its original size.