Remove MDM from iPhone 13

Edit to post above.

It would not hurt if you want to perform a Factory Default Reset on the phone as a last resort try, but based on experience I am not convinced that it will help.

Make sure that you have a new complete backup of the phone on iCloud or a computer before you erase the phone.

Old job, and some online research, says I might need to to a factory reset and not restore from a backup. Is it possible to do this but get back the 10 years of photos, notes, passwords etc etc?

Unfortunately, you have already answered your own question earlier in your post.

"I have contacted them and asked for them to remove the MDM profile, which they say they have done by the message and profile are still there."

That MDM profile will remain on your phone until your old company removes it, which they obviously have not done.

You can perform a Factory Default Reset on your phone, but the MDM profile will still be there, no matter whether you use a backup or don't use a backup of the phone.

Can you clarify please? You told us that the profile was still there after you contacted your former company and they told you the MDM had been removed.

"I have contacted them and asked for them to remove the MDM profile, which they say they have done by the message and profile are still there."

Simply powering the iPhone off and then back on would constitute a "reset".

Your former company did not remove the MDM Profile. If they had, you would not see it after you restarted the iPhone.

If you perform a Factory Default Reset, this will erase your personal data on the phone.....but....it will not erase the MDM settings on the phone.

You will lose all of your personal data unless you have a backup that you can use to restore back to the phone when you set it up again. But, there is no need for you to do this because the MDM settings will not be removed from the phone during this process.