How do you take off a fan clutch for 2000 s10?

Very carefully. :) Seriously, the use of a spanner nut wrench/pin wrench is this proper way to do it. There is a tool called a pin wrench that has 2 pins that are perpendicular to the handle. The 2 pins are inserted into 2 of the 4 holes (not the bell pully bolt holes, but the 4 smaller holes that are between them) and used to hold the bell pully from rotating. Then you take the correct size wrench or LARGE adjustable wrench to turn the large nut between the fan blade and bell pully. The threads are right hand. The nut turns off in the normal direction that you would remove a nut or bolt. it takes some force. The "shade tree mechanic" way is to remove 1 of the bell pully bolts. Then find a bolt that's longer than the bell pully bolt and screw it into one of the empty hole (as far as you can) and using a pry bar jambed between the bolt and the bell pully to restrain it from turning use the wrench or LARGE adjustable wrench to unscrew the large nut. I just did this procedure while changing a head gasket on a 2000 S10 2200 engine. Good luck.