error when removing user from calender

[GV IT]

i am trying to remove a user who has resigned recently.

when i try to remove her access for shared calendar, eg meeting room, i get this error message

commands used

Remove-MailboxFolderPermission -Identity meetingroomr21@goldxx.com.sg:\calendar -User songyinchai@goldxx.com.sg

Removing mailbox folder permission on "meetingroomr21@goldxx.com.sg:\calendar" for user "Chai XXXX".
[Y] Yes [A] Yes to All [N] No [L] No to All [?] Help (default is "Y"): A
There is no existing permission entry found for user: Chai XXXX.
+ CategoryInfo : NotSpecified: (:) [Remove-MailboxFolderPermission], UserNotFoundInPermissionEntryException
+ FullyQualifiedErrorId : [Server=SG2PR06MB3080,RequestId=7e58fa8c-11b1-40d7-90c3-52e6005d0c36,TimeStamp=12/3/2019 2:58:28 AM] [FailureCategory=Cmdlet-UserNotFoundInPermissionEntryException] FAEE1E13,Microsoft.Exchange.Management.StoreTasks.RemoveMailboxFolderPermi
ssion
+ PSComputerName : ps.outlook.com"

how can i removed her access in a proper way?

[#2]

Well the error says that no matching permission entry has been found. What's the current status of that user, did you happen to delete his account?

[#3]

the user is still active.
have not deleted his account.
i have reset his password and was able to login to his email.