First of all you "remove" the rambar(unless you rip the model from open iv and convert it to GTA again). second of all simply putting a diffuse texture on a wont make the rambar invisible, not even transparent. you need an alpha blended shader for the object to be transparent. to put it quite simply, no you cant remove the rambar. Although there are a few ways to de-emphasize it(if thats even a word)