sounds to me like you are selecting the vertices by hand instead of by vertex group. most source models should already have vertex groups, so I'll show you a convenient way to delete faces without anything touching what you want... usually.

• in edit mode, select all the faces of your model.
  
• go to the properties panel, and select object data.
  
• Look for the vertex groups tab.
  
• scroll through and look for the groups of geometry that you want to keep.
  
• select that vertex group and click on the deselect button.
  
• repeat for any other groups you want to keep.
  
• delete it.
  
  if the survivor model has multiple materials, you can use that section of material, to deselect vertices you want to keep for your survivor as well.
  
  a warning however! some vertex groups have stray vertices beyond the expected body point. using this method is not perfect, but it should get the job done, be patient and you'll get through it.
  
  Finally, if you have no need for the model's shape keys, you can always use tris to quads to make selecting edge loops easier.

Hi
Thank you for the help, but when I want to deselect the vertex group I want to keep Blender just pop " /!\ not yet implemented "

Originally posted by Buzzsaw:

Hi Thank you for the help, but when I want to deselect the vertex group I want to keep Blender just pop " /!\ not yet implemented " -

What version of Blender are you using?

The latest one,

2.79 and i just veryfied the cache files, 22 were missing and have been downloaded.

But it changed nothing I still can't select the vertices groups 1 by 1.

Here is an example of what is going on

https://steamuserimages-a.akamaihd.net/ugc/869615517002548921/C5EF0C9D7788EC408E6657D20FDCE3B7B670D492/

Originally posted by Buzzsaw:

Here is an example of what is going on -Image-

May I ask how you are selecting/de-selecting the vertices currently?