I have an old pc that does not boot up into windows, I want to use the ssd that is installed with Windows 10 for my new PC but not as the OS drive, only as storage for games. (I have a new m.2 for my new pc's OS)
How can I erase everything off the ssd installed in my old pc, ready for my new one without being able to boot into windows?
If you can get it to connect to the new computer, and make sure it isn't the boot up device selected for starting up the new computer, then you should be able to format the drive (after getting whatever you want off of it) while it is connected to the new device.
That is, again, if it will actually work in the new computer as a secondary drive. Some do/some don't.
Now if the drive is damaged, then all bets are off.