|I can't say for sure with that case because it's not in front of me but for that model it's probably one of these:|
1) Remove the front cover and slide the bracket/cage out that way.
2) The drive bracket swings out to allow access to the back screws or it slides off a rail.
But in either case it's the drive bracket/cage you have to manipulate and not the drive.
The only manual download from HP for that model:
doesn't look like it would cover that but if you have the original user guide you might check that.
I found these which may or may not apply to your model: