If it's temporary then just wait it out, however if it's a permanent ban from Sony, the only way you'll be able to play on your specific account with your characters is on a PC. If you do play it on a PC you will have to repurchase the software but your account will be available to play.
You are technically able to unlink an account however SE does not under any circumstances unlink, then link it again to different PSN account due to an agreement they've signed with Sony. For example if someone linked their FFXIV account to the wrong PSN account, there is absolutely no recourse for them.