Somewhere in the actor that owns the mesh you want to change collision response to, change it like so:
Mesh->SetCollisionResponseToChannel(ECollisionChannel::ECC_Pawn, ECollisionResponse::ECR_Block);
Somewhere in the actor that owns the mesh you want to change collision response to, change it like so:
Mesh->SetCollisionResponseToChannel(ECollisionChannel::ECC_Pawn, ECollisionResponse::ECR_Block);