Re: [Configuring init.d] MySQL Default configuration is blocking one of my instances on startup

[Rick James]

I think you need to ask the SEs/OPS team to permanently remove the mysql that came with the OS. (It is handy for the machine to be preconfigured with MySQL or MariaDB, but if you are doing anything serious with the machine, it is usually wise to upgrade the version.)

Your question implies that you have multiple "instances", but you did not mention how your multiple instances deal with 3306. Are you using VMs? Several ports other than 3306? Other? I ask this because it seems like the answer would obviate the problem.

That still leaves the question about whether you (non-root) can maintain the mysql instances. Is there a "mysql" group? Are you a member of it? Or maybe you need to ask them to add you to that unix group. See if this complains or works:
sudo -u mysql date