So to reiterate the process of getting a former windows 10 SSD drive to install Windows 7, again, here are 2 methods
Here are a couple ways to do what I was explaining:
Link:
"windows cannot be installed on this disk. The selected disk is of the GPT partition style."??
Method #1:
1. Boot up to installation DVD/CD.
2. Click install but don't follow through.
3. Press SHIFT-F10 to bring up console.
4. Type "diskpart"
5. Once inside diskpart type:
-> list disk (find the one you want to convert)
-> select disk 0 (select the one you want from the list)
-> convert mbr (should take a second or two)
-> quit
6. Continue with install
Method #2:
1. Boot up to installation DVD/CD.
2. Click install but don't follow through.
3. Press SHIFT-F10 to bring up console.
4. Type "diskpart"
5. Once inside diskpart type:
-> list disk (find the one you want to convert)
-> select disk 0 (select the one you want from the list)
-> clean (wait an hour or so until its done)
-> quit
6. Continue with install