Is it on your phone? Try the Photo & Picture Resizer App on Google store.

if on your lap top do you have any photoshop type programmes. that allows you to resize.

To lesson my pictures that I have taken on my phone or tablet, I email them to myself. When I add a picture to a email, it then comes up with an option to resize just above. I resize it, send to myself then when I open the email attachment, I save it and it is then saved in my photo gallery. Hope that this helps. Jen

If it is on a computer/laptop, and you have the Microsoft Windows photo editor, it is easily cropped and resized there. The photos I take with my camera are 7-8Mb, and cropping will get them around 1 Mb.