Foundation Concrete Pour - Key Groove
Remove the key notch forming planks and generally clean up the slab.
Remove key notch lumber sticks
While there is still water over the slab area you can do some preliminary clipping away at the concrete to get at the key notch lumber, but it is easier to see what you are doing once the water has gone.
Make sure you do not damage the rebar. Composite rebar is great in tension but does not like the shear force that a jackhammer can exert.
This is what it should look like once the key notch lumber has been removed...
Trim concrete and clean slab
Remove wood blocks
At some point the wooden blocks that supported the walkway planks need to be removed once the concrete has set. You will be left with square holes in the concrete slab which will be filled in on a later concrete pour (eg when pouring the walls). Until you are ready to fill the holes it is best to leave the wood blocks in place so you don't trip on the hole.