PS C:\Users\sr> Remove-CalendarEvents -Identity user@company.com -CancelOrganizedMeetings

Confirm
Are you sure you want to perform this action?
The meeting(s) will be canceled and removed from the calendar. This action cannot be undone.
[Y] Yes  [A] Yes to All  [N] No  [L] No to All  [?] Help (default is "Y"): a
Error on proxy command 'Remove-CalendarEvents -Identity:'user@company.com' -CancelOrganizedMeetings:$True -Confirm:$False' to server
VI1PR07MB1728.eurprd07.prod.outlook.com: Server version 15.20.1059.0000, Proxy method PSWS:
Cmdlet error with following error message:
Microsoft.Exchange.Data.Storage.SendAsDeniedException: Cannot submit message. ---> Microsoft.Mapi.MapiExceptionSendAsDenied: MapiExceptionSendAsDenied: Unable to submit
message. (hr=0x80070005, ec=1244)
Diagnostic context:
    Lid: 55847   EMSMDBPOOL.EcPoolSessionDoRpc called [length=7702]
    Lid: 43559   EMSMDBPOOL.EcPoolSessionDoRpc returned [ec=0x0][length=156][latency=2]
    Lid: 52176   ClientVersion: 15.20.1059.0
    Lid: 50032   ServerVersion: 15.20.1059.6015
    Lid: 35180
    Lid: 23226   --- ROP Parse Start ---
    Lid: 27962   ROP: ropDeletePropsNoReplicate [122]
    Lid: 27962   ROP: ropSetProps [10]
    Lid: 27962   ROP: ropFlushRecipients [14]
    Lid: 31418   --- ROP Parse Done ---
    Lid: 55847   EMSMDBPOOL.EcPoolSessionDoRpc called [length=121]
    Lid: 43559   EMSMDBPOOL.EcPoolSessionDoRpc returned [ec=0x0][length=352][latency=87]
    Lid: 52176   ClientVersion: 15.20.1059.0
    Lid: 50032   ServerVersion: 15.20.1059.6015
    Lid: 35180
    Lid: 23226   --- ROP Parse Start ---
    Lid: 27962   ROP: ropSetProps [10]
    Lid: 27962   ROP: ropSubmitMessage [50]
    Lid: 17082   ROP Error: 0x4DC
    Lid: 27745
    Lid: 21921   StoreEc: 0x4DC
    Lid: 27962   ROP: ropExtendedError [250]
    Lid: 1494    ---- Remote Context Beg ----
    Lid: 37692
    Lid: 44092
    Lid: 64952   StoreEc: 0x3EB
    Lid: 40748   qdwParam: 0xF01000000000001
    Lid: 57132   qdwParam: 0x0
    Lid: 36423
    Lid: 42092   StoreEc: 0x4DC
    Lid: 58476
    Lid: 45434   Guid: 6a332b69-deb0-49d4-bb04-0b48da557f2a
    Lid: 10786   dwParam: 0x0        Msg: 15.20.1059.000:VI1PR07MB1728:c2386d8d-7ae1-4f94-9aef-9dc88a31b67d
    Lid: 1750    ---- Remote Context End ----
    Lid: 31418   --- ROP Parse Done ---
    Lid: 22753
    Lid: 21817   ROP Failure: 0x4DC
    Lid: 60547   StoreEc: 0x4DC
    Lid: 21966
    Lid: 30158   StoreEc: 0x4DC
   at Microsoft.Mapi.MapiExceptionHelper.InternalThrowIfErrorOrWarning(String message, Int32 hresult, Boolean allowWarnings, Int32 ec, DiagnosticContext diagCtx, Exception
innerException)
   at Microsoft.Mapi.MapiExceptionHelper.ThrowIfError(String message, Int32 hresult, IExInterface iUnknown, Exception innerException)
   at Microsoft.Mapi.MapiMessage.SubmitMessageEx(SubmitMessageExFlags submitMessageExFlags)
   at Microsoft.Exchange.Data.Storage.MapiAccessor.SubmitMessageEx(Object mapiObject, SubmitMessageFlags submitFlags)
   --- End of inner exception stack trace ---
   at Microsoft.Exchange.Configuration.Tasks.Task.ThrowError(Exception exception, ErrorCategory errorCategory, Object target, String helpUrl)
   at Microsoft.Exchange.Configuration.Tasks.Task.WriteError(Exception exception, ErrorCategory category, Object target)
   at Microsoft.Exchange.Management.StoreTasks.RemoveCalendarEvents.InternalProcessRecord()
   at Microsoft.Exchange.Configuration.Tasks.Task.<ProcessRecord>b__93_1()
   at Microsoft.Exchange.Configuration.Tasks.Task.InvokeRetryableFunc(String funcName, Action func, Boolean terminatePipelineIfFailed).
[Server=AM4PR07MB3377,RequestId=73bd3721-c253-4c71-8ebd-077bd59d0347,TimeStamp=17/08/2018 08:03:54] .
    + CategoryInfo          : NotSpecified: (:) [Remove-CalendarEvents], CmdletProxyException
    + FullyQualifiedErrorId : Microsoft.Exchange.Configuration.CmdletProxyException,Microsoft.Exchange.Management.StoreTasks.RemoveCalendarEvents
    + PSComputerName        : outlook.office365.com