Can I replace a bit of a cinder block wall with wood post to support a deck?
As mentioned in the comment above, the post which is all you should need on the corner, needs to be mounted on a concrete pier that goes to the frost line for your area. If there are other areas of your deck that are supported soley by a post or block on the slab that will rise or fall as ice forms and melts under the slab, needs to be resupported by concrete piers that go the frost line