Non-UK citizen/resident required to file Self Assessment

Hello, What is the appropriate way to communicate to HMRC that one is no longer in the UK or employed the UK? I have been charged a late fee for not filing my self assessment, which I did not believe needed to filed since I'm not a citizen, resident, in the UK, or employed by an entity in the UK in any capacity. I was previously on a tier 2 visa. Thank you for your help, Karl

Hi Karl,
You are required to submit a Self Assessment tax return every year until you no longer meet any Self Assessment criteria.
You can notify HMRC of your change in residence circumstances by completing the 'Residence, remittance  basis etc'  pages of the outstanding return (plus any other approprate pages).
More information can be found here:
Tax if you leave the UK to live abroad
Thank you.