Basic map editing assisance requested!

I am a server owner looking for some assistance in doing basic modifications to an existing map. I am just looking to delete certain existing vtfs around the map and add custom decals I have tried generating my vfts and vmts properly configuring the vmts. I have applied the vtf in hammer and generated my materials file to upload to the workshop so that my players can see it, although this did not work and I am at a stand still at this moment. I would appreciate if anyone could help me out and possibly add my discord tyrellm0ris#7374, Any assistance is appreciated.