Painting Materials not working

I have painted materials such as gravel, grass and more rocks earlier on, painting them was working fine.
Then I created a Pebble and Moss texture, however; whenever I tried to save one of them in the Textures folder it gave me an error:
“Asset /Game/StarterContent/Textures/Moss_LayerInfo already exists.”
I chose "Weight-Blended Layer (normal) by the way and I tried deleting the materials and textures and then creating them again,

pls help