How do I remove these?

I have these 3D models extracted from a game, but there is something wrong:

As you can see, there are these unwanted lines on the model, such as on the bottom of the feet. I want to remove these, but I can’t.

could you join the blend file?

Hmm. You want me to upload the .blend file? I’d prefer not to, because i have multiple models with this issue. I did a subdivide, and removed the extra vertices manually, but it increased the file size dramatically.

Looks like bad bone->vertex assignment. Whatever is affecting this model, could be affecting others. Or, if it is not rigged yet, it could be a bad import.
Without a .blend, any one, it is difficult to say for sure.