If the drum is full of water (door lock stays engaged/water level visable) and pump is clear and running on drain cycle then blockage is most likely in rubber drain which connect drum to pump... (Circled in blue)

Note: There is no way of removing this without draining the drum at the same time! If you can see water level then there is at least a bucket's worth of water which you much not want to just tip on your floor...

If washing machine can easily be moved outside or to a wet room (remember it's heaver than normal because it's full of water & cloths!) then that's best options. Where ever you do this it will be much easier with machine either on it's side, lend left hand side on against a wall (45 degrees) or standing on bricks/blocks

Either way, the machine needs to be stable (not at risk of falling on you, and ideally your are able to access the bottom of machine can get washing up bowl under where drain (circled in blue) connect to drum. Whilst it's technically possible remove rubber drain through rear of machine access cover, you will have not way to stop flood

The small (pump end) of rubber drain hose is attached with metal spring clip - squeese the to short thick metal wire ends and it should pull off of pump. Undoing this might release a bit more water, but blockage is probably above the ball at bottom of the drum.

The big end the connect to drum is a PH2 compression clasp - a PH2 screwdriver should fit directly behind the motor wiring to lose this. When this is loose the rubber should ease of of the plastic drum outer. Note this may release a lot of water!