Does anyone know how to get rid of these events in my calendar - I accidentally accepted something when a pop up came up and now these events keep occurring

If running iOS 13 or earlier versions, check: Settings - Passwords & Accounts - Accounts - Any rogue entries here? If so, delete the rogue account. 

If running iOS 14, check: Settings - Calendar - Accounts - Any rogue entries here? If so, delete the rogue account. 

Remove spam from Calendar on your iPhone