You don't want to present yourself in person to deal with this, AND they will NOT deal with it over the phone. There are privacy issues & laws that prevent personal situations from being handled over the phone (like, how do they know you are you?)
Write to them, or use e-mail/fax. Present them with your FL date of residency: rent/utility bills, driver's license change-over, insurance proof, veter's registration card, etc. that proove you do not live in PR
anymore. The IRS might actually be helpful here, if you can proved a statement from them that you filed taxes (either FL or US) for the years in question. Contact your local IRS office (check the Federal building) and tell them you need a Statement of Tax Filing for the appropriate years - it's a computer generated form letter. Bring picture ID, your SS card, and your tax copies for the years you need the letter.... you don;t want to mail or fax copied of your actual taxes unless you absolutely have to. Request a letter stating that you DO NOT owe and did NOT have to file PR
taxes for the years in question, and confirmation that the debt has been stricken from your record.
As with mud, life, too, slides by.