I can't delete any photos off of my Samsung Galaxy Core Prime. Why is this?

A

AC Question

When I plug it into my laptop, select the photos that I want to delete and press the delete button, it says that
"The storage is write-protected. Please remove the write-protection before proceeding"
When I try and delete them from my files on my phone, it said that it "Failed to delete"; btw I can't access my gallery because my storage space is too low and won't let me view my photos through there. Is there anyway to fix this?