2 shaders on one mesh how to delete one

hi

i have importet an modell from blender in unity there are 2 shaders on it
one for nearly the hole modell and one for only 2 smal parts
know when i change the texture during runtime only the smal parts change their texture that sucks!
does anyone know how to delete one of this shader and why unity created them

324620--11446--$2_shaders_problem2_940.png

Expand the material section of the mesh renderer in the inspector. Set the size of the array to 1.