Here’s a useful powermt command to use to clear PowerPath errors after removing LUNs from a host. Note that you will prompted whether to remove each possible path to the target, usually 2 to 4 times per LUN.

Microsoft Windows [Version 6.1.7600]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

C:Windowssystem32>powermt check
Warning: CLARiiON device path c0t0d11 is currently dead.
Do you want to remove it (y/n/a/q)? y
Warning: CLARiiON device path c0t1d11 is currently dead.
Do you want to remove it (y/n/a/q)? y
Warning: CLARiiON device path c1t0d11 is currently dead.
Do you want to remove it (y/n/a/q)? y
Warning: CLARiiON device path c1t1d11 is currently dead.
Do you want to remove it (y/n/a/q)? y

C:Windowssystem32>