I have accidentally uploaded my development environment APN where I wanted my production APN .p12 file in Firebase. However I cannot remove it now. There are a button that says "Upload new", which I have tried, but afterwards there are still the old development APN .p12 file.
I have as well tried to delete the iOS app and then install it again, but the keys are still stored under "Cloud Messaging".
How am I able to delete an APN key?
This same problem happened to me.
However the following workaround does the trick for me:
I have found a workaround to the problem. You try generating a new certificate with a different private key and then try to overwrite the old certificate using that new certificate at Firebase settings.