Howdy Pard!
I use a quality photo edit program, and it don't really matter which photo edit program you use, it should give you options to resize your photo. If you have the option to crop, you should have the option to resize. I usually resize mine to 640 x 480 pixels. That should drop your photo down to around 100kbs. Easy peazy.
All that cropping will do is to take a portion of your photo and isolate that, but usually will still present the remaining image in a file just about as large as the original. Cropping just ins't the answer for your situation. It works fine if you say, took a photo of a location or some item, and discover there is something in the photo that you wished wasn't there. Cropping allows you to draw a box around that part of your photo that is desirable, while eliminating stuff outside that box that you don't want to see in the finished product.
Resize is the way you'd want to go.
Most photo editing programs will allow you to resize, but also adjust your photo for brightness, contrast, color saturation, and a whole bunch of other items.
Maybe this should be the subject for another video for me to produce.
Blessings,
M-Taliesin