I need to remove a

Removing the casing of a notebook is a tough job. Even after removing the screws, the covers won't come out. The reason being the clip locks aroung the edge.
Slowly pull apart the two sides (top and bottom) from one place and push a screwdriver through the opening. (Don't push it too far or you will damage the circuitry). Push another flat screwdriver inside close to the first one. Slowly drag the second one along the edge. If the casing resists opening at one place that means there is a clip lock there. Slowly push the screwdriver handle downwards. If you are lucky, the lock will open. If it doesn't work push the screwdriver handle upwards. (I've not opened this particular type of computer, so you have to check and see). Once a lock opens insert the first screwdriver there to prevent it from closing again.
Slowly work around the edge to open all locks.