The frame and close button for aero theme are located in a Steam image #971 in the .msstyles.
The top frame for the basic theme are image #934, 964, 960, 951(depends if the window is maximize minimize or somewhere in between) in the .msstyles.
I would recommend that you create a new custom theme so you do not corrupt the original, look at Post #38 Here it will show you how.
If you plan on doing a lot of editing to the .msstyles I would recommend buying Ave's Windows7 Style Builder is the easiest way to make a custom theme. This program also breaks down at Steam image #971 into individual locations.
Jerry
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Sorry I didn't get back to you sooner I've been sick.
The .msstyles is in C:\Windows\Resources\Themes\Aero folder, but like I suggested earlier you should create a new theme from scratch so you do not corrupt the original look at Post #38 Here it will show you how.
I have no idea how to remove the icon in the top left corner.
To change the top frame you'll need to edit the images(with a image editor of some kind) at Windows and Caption Buttons > Aero > Dwm Window > Frames > Normal > Top
The close button would be at Windows and Caption Buttons > Aero > Dwm Window > CloseButton > Normal Button
The first time you click on the Edit button it will ask you to set a default image editor you will have to navigate to its .exe to set it.
Jerry
My Computer
At a glance
Win 7 Pro x64 / Win 10 ProIntel(R) Core(TM) i7-3630QM CPU @ 2.40GHz12 GB(1) Intel(R) HD Graphics 4000 (2) NVIDIA GeFo...
Computer type
Laptop
Computer Manufacturer/Model Number
Sager NP9170
OS
Win 7 Pro x64 / Win 10 Pro
CPU
Intel(R) Core(TM) i7-3630QM CPU @ 2.40GHz
Motherboard
CLEVO P170EM
Memory
12 GB
Graphics Card(s)
(1) Intel(R) HD Graphics 4000 (2) NVIDIA GeForce GTX 675M
Sound Card
(1) Realtek High Definition Audio (2) Intel(R) Display Aud
Monitor(s) Displays
17.3
Screen Resolution
1920x1080
Hard Drives
(1) Samsung 860 EVO 500GB(OS) (1) Samsung 860 EVO 500GB(Data)
Keyboard
Backlite
Antivirus
MSE, Malwarebytes Pro
Browser
Firefox
Other Info
DESKTOP: Custom-built.
OS: Win 10 Pro x64.
CASE: Rosewill R5.
CPU: Intel I5 4670K CPU @ 3.40GHz.
CPU COOLER: Cool Master Hyper 212 EVO.
MOTHERBOARD: Asus Z87-A.
MEMORY: Kingston HyperX 2x4 GB.
GPU: Nvidia Geforce 650 TI.
PSU: Corsair TX750.
DRIVES: (1) Samsung 840 120 GB SSD (2) Western Digital blue 500 GB 7200 RPM.