Look similar to the Superstar ones i did the other day.
You need to gently tap around them from the other side,with a long thin punch.
On one we had to find an axle that was a good fit into the adaptor and gently tap it from side to side,to get the retaining ring to move.
Its an adaptor that fits against the bearing,that then has a reatining coller pressed in to stop them falling out.
They are a nightmare as there is no way of removing them.
I am wondering if you brought a big expanding floor bolt,if you could expand it in the adaptor only and then knock it out from the other side