Hi @JAI
We could use the command Search-Mailbox to meet this need, delete all recurring meeting created by the user and remove them from attendees.
Get-Mailbox -ResultSize Unlimited | Search-Mailbox -SearchQuery "kind:meetings AND Subject:'Test1' AND From:username@contoso.com" -EstimateResultOnly
Get-Mailbox -ResultSize Unlimited | Search-Mailbox -SearchQuery "kind:meetings AND Subject:'Test1' AND From:username@contoso.com" -DeleteContent
The first command using parameter -EstimateResultOnly returns an estimate of the total number and size of messages. Messages aren't copied to the target mailbox. You don't need to specify a value with this switch.
The second command using parameter -DeleteContent switch specifies that the messages returned by the search be permanently deleted from the source mailbox.
Note1: The Search-Mailbox cmdlet returns up to 10000 results per mailbox if a search query is specified.
Note2: You need to be assigned the Mailbox Import Export management role to use this -DeleteContent switch.
This similar thread for your reference: Delete or cancel recurring meeting invites
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