Computer level 10 is 2600 rating. So yeah, unless you are a super GM you have no chance. I suggest you practice vs players marginally better than you.
How to win against the computer?

Yikes...some extremely dubious play there. First thing you must do is not hang your pieces. Fundamentals...develop all your stuff, don't move the same piece twice in the opening unless absolutely necessary, castle your king...most important of all even if you have no clue what to do just don't lose material. Do all this and you will gain 200+ rating by beating players who don't do all this.
Been trying to practise chess by playing against the computer but just seems impossible to beat especially with it at level 10 and me being the black pieces. Surely playing with the black pieces you have to rely on your opponent blundering and you have to spot the blunder and take advantage of it? Therefore surely it's impossible to beat the computer as especially at level 10 it'll just play the best possible moves and make no mistakes?