How to unscrew this screw
The plastic should be flexible enough to bend a little.
Put the end of the screwdriver in the head of the screw and then try to force the screwdriver in or more strait while turning it. Apply pressure up into the screw as you turn it as well.
Somebody got it in, you should be able to get it out.
If you can not get it out or the head strips you could cut the screw with a mini hacksaw.