Persistent Calendar error message

Hello all,

i use the Apple calendar app both on Mac & iPhone. While my Mac was offline I rejected a meeting request from there, and thought my response would go out once back online. Once I went to my iPhone’s calendar app I saw it as still in the inbox even though it was sent from the Mac app. So I rejected invite from my iPhone as well to be sure it was sent.

since then I get annoying interruptions about every half an hour from iPhone’s calendar telling me my invite response wasn’t sent yet (see screenshot).

is there a way I can remove that invite response from the Calendar’s records? Thanks!