I think this blur that you refer to is in fact Deep of field effect, please check the update v1.1 first, with updated and better effects.
But if you still want to remove this effect.
in F1 2015 folder, go to:
ReShade\Presets\Shaders_by_MartyMcFly.cfg
change this line
#define USE_DEPTHOFFIELD 1 //[DOF] //-
Set to Zero
#define USE_DEPTHOFFIELD 0 //[DOF] //-
But if you still want to remove this effect.
in F1 2015 folder, go to:
ReShade\Presets\Shaders_by_MartyMcFly.cfg
change this line
#define USE_DEPTHOFFIELD 1 //[DOF] //-
Set to Zero
#define USE_DEPTHOFFIELD 0 //[DOF] //-
Hope this helps.