If I have read this right, you are having problems physically removing the CD rom. I have a Compaq Presario S6000NX. I'm sure you know about shutting off the machine & ETC, so I won't go in to that.
If you have the same machine or similar, remove the side cover. Look for plastic "snap" tabs along the edge of the front. Pressing on them untill they release. Be carefull when pressing on them as they will break. Remove the front cover. Unplug the cables to the DVD devices you want to remove. You will notice that there is a green plastic attachment on the side of the frame that holds the HD & DVD device. Lift the tab that holds the device just enough to release the screws and at the same time push the back of the device twards the front. Be carefull as it is friction slide & may pop out & drop out, damaging it. Through some reading, I have come to the conclusion that if you select "cable select" on the devices, the computer works faster in accessing data. Instalation is just the reverse. Don't forget to remove the screws from the old device & put them in the same place as the old one. If you only have one DVD or HD installed, if Compaq did their job, you will see 4 extra screws below the divice slot. As a side note, the HD is removed & installed the same way.
Hope this helps.