Removing specific part of armor mesh problem

[Kamila11101]

Hi,
Recently I found good armor for my character but I don't like few parts of this armor.

So I tried to remove them but:
1 My first attempt end like this:

2)Another end like this:

3)and on the last I get CTD.

So I want to ask if somebody could remove those parts.
Crimson Twlight Armor CBBE
Crimson Twilight Armor CBBE HDT Bodyslide ( I overwrite main armor with this and then builded an armor)