The only thing I can guess is the file path issue.
I see there is a new line at the end of the path:
Warning: unlink(/home/syxbit/public_html/mysite.net/upload/uploads/images/Flip Flops.png
HERE IS A NEW LINE?
Is it exact what it is? Maybe you can try to “trim()” it to see the result.
Also something you may have a try:
1. Try a path without space.
2. Change file permission to 777 and try it again.