Back to firmware original Archer C2600 V1.1

I have a TP-Link Archer C2600 router with LEDE on it. I want to go back to the original firmware. I really saw tutorials and I did not find the right solution. Would you know how to tell me or how to restore the original firmware? I really do not know how to solve this problem! Thank you very much for what you can do.

I tried several methods like using Putty and WinSCP, but when I flashed it gave me an error like
Unable to open device mtd: firmware Can not open the device to write! I tried several other ways but when flashing the original I gave that error, I think it is a problem that is not the correct command hopefully can help me. regards

Follow the info on this page, under the section titled 'Debricking'.

Make sure you disable Windows Firewall.