Help to remove fan extension????

[OUbesto]

Hey guys, I am replacing my stock radiator and replacing with a Champion aluminum with twin 14" electric fans. In order to get enough clearance, I need to remove the current fan blade from the water pump pulley assembly. Once I removed the fan, I cannot figure out how to remove the 2" metal extension (See photo) from the black upper pulley. It does spin around but does not come apart. I dont want to take a hammer to it so I thought I get some real expert advice here on the forum. I'm thinking that I need to remove the pulley from the water pump shaft and then maybe there is a screw or something that holds the two pieces together from the inside???? Anyone know?

1970 C-10 402, HT400, AC