How do i go about Deleting images from phone when it's saying failed

[Kdf1]

My phone is a Samsung s6 edge and it has been saving all media sent to my phone via fb messenger. I want to delete the images but it won't let me it says failed. When i go to my files to delete from there I can't find the images, but they are still in my gallery. When I try to delete the folder it wont do that either. Please help there are some images I'm not happy about, that have been sent to my phone thanks kdf

 

[CrimsonBurns]

Is there an option in gallery to delete the photos? I don't know much about Samsungs.

 

[CrimsonBurns]

Alternatively, if you can, move your photos into a folder then plug your phone into a computer then delete them from there.