CEO of the company had a rule to auto forward his calendar items to his personal secretary. Unfortunately, after about a year of service, this person was moving to another position.

The new IT rules stipulate that unless written permission from the VP of IT, President of the company, or CEO is provided that under no circumstances should IT actively connect to another user’s email box.

This makes it harder since the old way was to grant full permissions to their mailbox, attach it as a non-cached account, and then make any necessary changes.

The CEO was also travelling out of the country, so getting him on a phone call would prove difficult.

Powershell to the rescue! I did the following commands from the Exchange admin server, but this will work just as well right on the Exchange servers themselves, or even if you load the PS1 for exchange.
Get-inboxrule -mailbox USERNAME | fl > c:\text\outlookrules.txt
I opened this text file and searched for the name of the secretary – found one rule “If the message is meeting, forward to”

We can disable or remove the outlook rule as well.
disable-inboxrule -mailbox USERNAME -identity "THELONGNUMBERIDENTITYFROMPREVIOUSSTEP"
or
remove-inboxrule -mailbox USERNAME -identity "THELONGNUMBERIDENTITYFROMPREVIOUSSTEP"