Without the amount of corrosion that you have, my fan pulley is a little stiff to get off. You may need to utilise a rubber persuader and a little bit of rust shifter such as penetrene on yours.
The pulley needs to be "loosened and then "'walked off".

You need to remove this pulley to get at the bolt that holds the "y" bracket on to the engine block.

You can remove the tensioner without taking the Y bracket off but it makes the job a lot more difficult for the shade tree mechanic.

I'd suggest that the fan clutch is cactus. New one required. Its probably rusted up anyway.