Do I need to remove mesa drivers before installing AMD drivers ?? tried looking up but all that comes up is how to remove drivers.
No, there is no need to remove mesa before installing AMD's driver. And the answer by Suditu George is almost completely incorrect. AMD does provide drivers for 16.04 in the form of AMDGPU-PRO.
Elementary os 0.4 is based on Ubuntu 16.04 wich does not support AMD GPU's. If you need intensive gpu rendering you will have to go down to elementary 0.3. But the open amd driver is quite fast.