I built an sbr many years ago. Engraved, I was "manufactuer". Want to get it off registry. Process? Thanks.

From Prince Law

https://blog.princelaw.com/2009/03/25/batfe-letter-requesting-removal-of-a-sbrsbs-from-the-nfrtr/

Below is a generic letter that can be sent to the BATFE when an individual wishes to convert a Title II firearm (short barreled shotgun or short barreled rifle) back into a Title 1 firearm. If you want a Word version of the below form, click here. You should send the letter certified mail and keep the receipt because even though the letter requests a confirmation, the BATFE is notorious for not responding.

Director
Bureau of Alcohol, Tobacco, Firearms and Explosives
Attention: NFA Branch
244 Needy Rd
Martinsburg, WV 25405-9431
RE: Removal of a SBR/SBS from the NFRTR

To Whom It May Concern:

I would like to advise the NFA Branch that a [Short Barreled Shotgun OR Short Barreled Rifle] previously registered by me on a Form 1 has been permanently returned to a Title I status firearm. I am respectfully requesting that the National Firearms Registration and Transfer Record (NFRTR) be modified to reflect this change in status. Lastly, I am sending this letter in duplicate and request that one copy be returned to me along with a letter stating that NFRTR has been modified to reflect the change in status.

Name & location of original manufacturer: _____

Type of firearm: _____

Caliber, Gauge or Size: ___

Model: ___

Length of barrel: ____ (now returned to ”)

Length overall: ____ (now ”)

Serial number: ____

Thanking you in advance, I am

[Typed Name]

Include:

•Two Copies of this Letter
• Previously Executed Form 1

You can't.
Osprey21 is correct. It'll stay on the NFRTR forever.

Also... you were the maker, not a manufacturer (unless you happened to hold a Type 07 FFL at the time).

If you don't want it to be a Title II (NFA) SBR anymore, just make it physically not a SBR. Done.
It's that simple. Then you can go ahead and treat it as a Title I (GCA) normal firearm for transfers, etc. No notification letter is required. (ATF does prefer one however.) You could send it after any sale/transfer, if you choose to send notice.

If you're describing an AR, you should just keep it (unless you plan on giving it away).
It's hard to sell a personally-engraved AR lower, when a potential buyer can purchase a stripped one new for $40.

I've done this many times. They will send you a letter indicating they have UPDATED the registry. It's good to have that on file or pass that along to the new owner if sold.

Why? Lowers are cheap just take it apart and toss the register lower in the safe

My only worry, without documentation from the ATF, would be if I sold an SBR that was at the time a non NFA firearm and the new owner converted it and the ATF thought I sold it illegally.

Otherwise, I’d never update the registry.

You don't even need to worry about that.   You're not required to tell them you un-NFA'ed it.

If you're not selling it, there is really no reason to un-NFA it permanently.  You can just toss a 16" upper on it and go about your business.   They're always going to know you had it.

For that matter, there is no reason to sell it either - the stamp costs more than a new lower.