Re-Register device deleted

Hi, I’m new to the TTN and LoraWan world, I made a big mistake and need help to see if it would be possible to fix it
I bought a heat and hot water meter emitted by Lora. I registered them in TTN with OTTA and everything ok, the problem is that I added them in the same application and discovered that it had a different decode function then, without thinking, deleted the devices, created two different applications and tried to re-register the devices (which never stopped broadcasting) but without success either by ABP (I do not know the Network Session Key and the App Session Key that TTN assigned the first registration), I only keep the Device Address.

This device Address is in the Traffic section of the Gateway Overview but in applications the device appears as never seen. Would there be any possibility of permanently deleting the devices to re-register them or access the information to register them again via ABP? Thanks in advance

Registering them again on TTN is not the problem. Your devices still consider themselves ‘bound’ to TTN.
You need to find a way to reset the devices. Usually that is information found in the manual.

I have done what you told me and everything works fine. Thanks a lot