A shared processor pool cannot be deleted. However, it can be deactivated by setting the maximum pool capacity back to 0. However, no LPARs may be assigned to the shared processor pool:

$ ms chprocpool ms11 benchmark max_pool_proc_units=0
hmc01: chhwres -r procpool -m ms11 -o s --poolname benchmark -a 'max_pool_proc_units=0'
ERROR: remote HMC command returned an error (1)
StdErr: HSCL3614 The shared processor pool cannot be unconfigured since at least one partition is using the shared processor pool.
$

The LPARs assigned to the shared processor pool must first be reassigned to another shared processor pool.

$ lpar chprocpool lpar1 DefaultPool
$ lpar chprocpool lpar2 DefaultPool
$

The shared processor pool can then be deactivated without any problems:

$ ms chprocpool ms11 benchmark max_pool_proc_units=0
$

And is as a result no longer displayed by default:

$ ms lsprocpool ms11
MS_NAME  PROCPOOL     ID  EC_LPARS  RESERVED  PENDING  ENTITLED  MAX
ms11     DefaultPool  0   0.80      -         -        0.80      -
ms11     testpool     1   0.00      0.40      0.40     0.40      2.00
$