why the texture of garment also applied into flesh? help me

Hi, im new to this modding community and interested in learning how to mod.

im starting with simple things first. but the problem is i encountered an issue regarding the texture of an edited mesh. i dont know how to explain t properly so i'm gonna let the pictures speaks.

so i'm interested in this cute top right,





and im trying to mod it by removing the white T-shirt. i extracted the mesh and edited it with blender and then when i imported back the mesh to the sims studio, it become like this:





the red arrows shows the part which i expected not to be textured because it should be the sim's flesh.

for the lower white part it's okay because i can just erase the texture for white T-shirt. but for the upper parts i dont know what to do about it, because it's behind the garment.

so I need help regarding this issue i encountered.

thanks.