How to sync Calendar in my MacBook air with my iPhone?

I would like to sync my MacBook air (M1 2020) iCal with my phone and my husband's phone. Under Calendar, Accounts on the mac, this is what shows:

iCloud,

my personal email address,

Gmail,

yahoo,

AOL. with my phone #, and

AOL. with his phone number

I have not used AOL for EONS, and in fact do not know any signin information from those days. I am trying to get our MacBook calendar to sync with our. phone calendars but cannot seem to remove the AOL accounts...and If I am successful in removing them, will I lose any info that is current (since I do not even have AOL any longer) Our phones communicate with each other and sync up on appointments added by either of us...but anything put into iCAL on the mac, does not sync with either phone, and the appointments we put on our phones do not show up on the mac. I hope the fix is not too complicated.

[Re-Titled by Moderator]