Building made 10years ago out of feather-lite cmu's(cinder blocks) On concrete slab.do I need to anchor the cmu's I'm putting in to the slab,sides,top? I'm removing the exterior barn door hardware and door.and basically trying to make it look like it was never there

It would be a good idea to I would go from the sides

Epoxy 5/8 rebar into existing slab. Top layer will not have rebar.
Fill the holes at rebar locations with concrete

Just one option...

http://i819.photobucket.com/albums/zz111/lacogada/blockwall_zps1283a1a7.jpg

You could also use brick ties from the side or metal wire wall ties.