How do you adjust the rear shocks to go from two up to one up riding?
How much is the wrench to do this job?
Could someone give a description of how to do this?

 

Wrench is not the real problem. However it helps to have one. The problem is breaking the lock nut. Its the kind of thing that you are not going to adjust back and forth. If you ride two up you will just need to tolerate the slightly rougher ride when you are solo. You need a torque wrench extension tool between breaker bar and crows foot wrench (what I use)