having trouble deleting pictures out of "my gallery"

this...about going onto Google and deleting the pictures on the computer and they will be gone from your phone WRONG!!! IT DID NOT WORK
 
For anyone having this issue in 2017, I found a resolution that worked for me. Make sure first that your cloud trash isn't full. I had to access my cloud trash and empty the trash which then allowed me to continue deleting pictures in my gallery. It worked for me, and was very simple to fix.

To access the Samsung Cloud Trash, simply go to the settings on your My Gallery app and scroll down to Trash. Select and it will reveal everything you have pending in trash. Choose to Empty Trash and viola. You should be able to return to the app and continue deleting.