- Open your console.
- In the input field write: 
 cl_draw_only_deathnotices 1
 If you want to show the HUD again input:
 cl_draw_only_deathnotices 0
You can also use another command, if you also want to hide the crosshair but the you need to Enable Sv_cheats.
cl_drawhud 0 
and to show again 
cl_drawhud 1
 
              